The Periodic Table C

Previous Page Next Page Next PageContents Contents

Previous Page

ElementsContents 3The Periodic Table 8Hydrogen H 1 9Helium He 2 13Lithium Li 3 16Beryllium 19Boron B 5 22Carbon C 6 25Nitrogen N 7 30Oxygen O 8 33Fluorine F 9 36Neon Ne 10 39Sodium Na 11 42Magnesium Mg 12 45Aluminium Al 13 48Silicon Si 14 52Phosphorus P 15 56Sulfur S 16 59Chlorine Cl 17 63Argon Ar 18 66Potassium K 19 68Calcium Ca 20 71Scandium Sc 21 74Titanium Ti 22 77Vanadium V 23 81Chromium Cr 24 84Manganese Mn 25 87

The Periodic Table of the Elements

Created by: Paul Morlang of Schenectady, New York

Designed at: Dragin My Feet Software - 2014Home of Educational Software

Contents


Previous Page

Iron Fe 26 90Cobalt Co 27 95Nickel Ni 28 98Copper Cu 29 102Zinc Zn 30 106Gallium Ga 31 109Germanium Gm 32 112Arsenic As 33 114Selenium Se 34 116Bromine Br 35 118Krypton Kr 36 120Rubidium Rb 37 123Strontium Sr 38 126Yttrium Y 39 129Zirconium Zr 40 132Niobium Nb 41 135Molybdenum Mo 42 138Technetium Tc 43 141Ruthenium Ru 44 144Rhodium Rh 45 147Palladium Pd 46 150Silver Ag 47 153Cadmium Cd 48 157Indium In 49 159Tin Sn 50 161Antimony Sb 51 164Tellurium Te 52 166Iodine I 53 168Xenon Xe 54 171Caesium Cs 55 174Barium Ba 56 177Lanthanum La 57 179Cerium Ce 58 182

Praseodymium Pr 59 185Neodymium Nd 60 187Promethium Pm 61 189Samarium Sm 62 191Europium Eu 63 193Gadolinium Gd 64 195Terbium Tb 65 198Dysprosium Dy 66 200Holmium Ho 67 202Erbium Er 68 204Thulium Tm 69 207Ytterbium Yb 70 209Lutetium Lu 71 211Hafnium Hf 72 213Tantalum Ta 73 215Tungsten W 74 218Rhenium Re 75 221Osmium Os 76 223Iridium Ir 77 225Platinum Pt 78 227Gold Au 79 230Mercury Hg 80 235Thallium Tl 81 238Lead Pb 82 241Bismuth Bi 83 244Polonium Po 84 246Astatine At 85 248Radon Rn 86 250Actinium Ac 89 253Thorium Th 90 255Protactinium Pa 91 258Uranium U 92 260Neptunium Np 93 265


Previous Page

Plutonium Pu 94 267Americium Am 95 270Curium Cm 96 272Berkelium Bk 97 274Californium Cf 98 276Einsteinium Es 99 278Fermium Fm 100 280Mendelevium Md 101 282Nobelium No 102 284Lawrencium Lr 103 286Rutherfordium Rf 104 288Dubnium Db 105 290Seaborgium Sg 106 292Bohrium Bh 107 294Hassium Hs 108 296Meitnerium Mt 109 297Darmstadtium Ds 110 298Roentgenium Rg 111 299Copernicium Cn 112 300Ununtrium Uut 113 302Flerovium Fl 114 303Ununpentium Uup 115 305Livermorium Lv 116 307Ununseptium Uus 117 309Ununoctium Uuo 118 311Group 1 Elements 313Group 2 Elements 314Group 3 Elements 315Group 4 Elements 317Group 5 Elements 318Group 6 Elements 319Group 7 Elements 320Group 8 Elements 321

Group 9 Elements 322Group 10 Elements 323Group 11 Elements 324Group 12 Elements 325Group 13 Elements 326Group 14 Elements 328Group 15 Elements 330Group 16 Elements 331Group 17 Elements 332Group 18 Elements 333Alkaline Metal Elements 335Earth Metals 335Non - Metals 336Nobel Gases 336Actinoids 337Lanthanoids 337Semi Metallic 338Transition Metals 339Transactinides 340Period 1 Elements 342Period 2 Elements 343Period 3 Elements 344Period 4 Elements 345Period 5 Elements 346Period 6 Elements 347Period 7 Elements 349Alphabetical List 351


Previous Page

Hydrogen

Hydrogen (Latin: hydrogenium) is the chemical element in the periodic table that has the symbol H, atomic number 1 and atomic weight of 1.00794. It is a Non-metal-lic gas.

• Name: Hydrogen• Symbol: H• Atomic number: 1• Atomic weight: 1.00794• Standard state: gas at 298 K• CAS Registry ID: 1333-74-0• Group in periodic table: 1• Group name: (none)• Period in periodic table: 1• Block in periodic table: s-block• Colour: colourless• Classification: Non-metallic

At standard temperature and pressure it is a colorless, odorless, non-metallic, univalent, highly flammable diatomic gas. Hydrogen is the lightest and most abun-dant element in the universe. It is present in water and in all organic compounds and living organisms. Hydrogen is able to react chemically with most other ele-ments. Stars in their main sequence are overwhelmingly composed of hydrogen in its plasma state. This element is used in ammonia production, as a lifting gas, as an alternative fuel, and more recently as a power-source of fuel cells.In the laboratory, hydrogen is prepared by reaction of acids on metals such as

zinc. For production in large scale commercial bulk hydrogen is usually manufac-tured by decomposing natural gas. Electrolysis of water is a simple although inef-ficient method. Scientists are now researching new methods for hydrogen produc-tion. One of them involves use of green algae. Another promising method involves the conversion of biomass derivatives such as glucose or sorbitol, which can be done at low temperatures through the use of a new catalyst.

Notable Characteristics

Hydrogen is the lightest chemical element with its most common isotope con-sisting of just a single proton and electron. At standard temperature and pressure

The Periodic Table of the Elements was created to fill a need. I went to the public li-brary looking for a book about the Periodic Table and could not find one, not one. The purpose of the book was to get information about the Periodic Table so i could create a software program called aPeriodic Table. I’ve wanted to do this for about 19 years so in 2007 i was diagnosed with a terminal disease and given 1 year to live. After living through that year and another one after that i decided accomplish something with the rest of my life. I taught myself Java and wrote the program aPeriodicTable. It can be downloaded at:

https://kickass.to/aperiodictable-t9575525.html or http://aperiodictable.webs.com/ The program aPeriodic Table comes in two sizes 1280x720 and 1920x1080. It is written

in Java, so you will need Java installed on your computer . Version 1.5 through 1.8 will work. One thing that is very important is that it needs to be installed at C:\aPeriodicT-able otherwise it will not work. With all that it should run any operating system like Windows, MacIntosh or Linix.Then with all that information and still living i decided to do more. I made a Periodic

Table.pdf and a Periodic Table.swf and i am working on the .epub version. I am hopeful that the trend continues, the staying alive part i mean. If so i plan to

create new educational software. Like Electrical Formulas, Physics Formulas and Math Formulas.

You can e-mail me at: [email protected]

The Periodic Table of the Elements

https://kickass.to/aperiodictable-t9575525.html

http://aperiodictable.webs.com/

mailto:[email protected]


Previous Page

conditions, hydrogen forms a diatomic gas, H2, with a boiling point of only 20.27and a melting point of 14.02Under exceedingly high pressures, like those found at the cen-ter of gas giants, the molecules lose their identity and the hydrogen becomes a liquid metal (see metallic hydrogen). Under the exceedingly low pressure conditions found in space, hydrogen tends to exist as individual atoms, simply because there is no way for them to combine; clouds of H2 form and are associated with star formation.This element plays a vital role in powering the Universe through the proton-proton

reaction and carbon-nitrogen cycle. (These are nuclear fusion processes that release huge amounts of energy through combining two hydrogen atoms into one helium atom.)

The Hydrogen Atom

A hydrogen atom is an atom of the element hydrogen. It is composed of a single neg-atively charged electron, distributed around the positively charged proton which is the nucleus of the hydrogen atom. The electron is bound to the proton by the Cou-lomb force.

Applications

Large quantities of hydrogen are needed industrially, notably in the Haber process for the production of ammonia, the hydrogenation of fats and oils, and the produc-tion of methanol. Hydrogen is used in hydrodealkylation, hydrodesulfurization, and hydrocracking.

Other uses: * The element is used in the manufacture of hydrochloric acid, welding, and the re-

duction of metallic ores. * It is used in rocket fuels. * Liquid hydrogen is used to perform cryogenic research, including superconductiv-

ity studies. * Since hydrogen is fourteen and a half times lighter than air, it was once widely used as a lifting agent in balloons and airships. However this use was curtailed when the Hindenburg disaster convinced the public that the gas was too dangerous for this purpose. * Deuterium, an isotope (hydrogen-2) of hydrogen, is used in nuclear fission applica-

tions as a moderator to slow down neutrons, and is also used in nuclear fusion reac-tions. Deuterium compounds have applications in chemistry and biology in studies of reaction isotope effects.* Tritium (hydrogen-3), produced in nuclear reactors, is used to construct hydrogen

bombs. It is also used as an isotopic label in the biosciences and as a radiation source in luminous paints. Hydrogen can be burned in internal combustion engines, and a fleet of hydrogen-burning cars is maintained by Chrysler-BMW (see Hydrogen car). Hydrogen fuel cells are being looked into as a way to provide power with lower emis-sions than hydrogen burning internal combustion engines. The low emissions of hy-drogen in internal combustion engines and fuel cells is offset by the polution created by hydrogen production.

History

Hydrogen (French for water-maker, from Greek hudôr, "water" and gennen, "gen-erate") was first recognized as a distinct substance in 1776 by Henry Cavendish. Cav-endish stumbled upon it when experimenting with acids and mercury. Altough he wrongly assumed that hydrogen was a compound of mercury (and not of the acid), he was still able to describe many of hydrogen's properties quite accurately. Antoine Lavoisier gave the element its name and proved that water was made of hydrogen and oxygen. One of its first uses was for balloons. The hydrogen was obtained by mixing sulfuric acid and iron. Deuterium, one isotope of hydrogen, was discovered by Harold C. Urey by distilling a sample of water multiple times. Urey received a Nobel Prize for his discovery in 1934. In the same year, the third isotope, tritium, was discovered.

Occurrence

Hydrogen is the most abundant element in the universe, making up 75% of normal matter by mass and over 90% by number of atoms. This element is found in great abundance in stars and gas giant planets. Relative to its great abundance elsewhere, hydrogen is very rare in the earth's atmosphere (1 ppm by volume). The most common source for this element on earth is water which is composed two parts hydrogen to one part oxygen (H2O). Other sources include most forms of organic matter (currently all known life forms), coal, fossil fuels and natural gas. Methane (CH4), which is a by-product of organic decay, is an increasingly important source of hydrogen.

Compounds

The lightest of all gases, hydrogen combines with most other elements to form com-pounds. Hydrogen has an electronegativity of 2.2, so it forms compounds where it is the more non-metallic and where it is the more metallic element. The former are called hydrides, where hydrogen either exists as H- ions or just as a solute within the other element (as in palladium hydride). The latter tend to be covalent, since the H+ ion would be a bare nucleus and so has a strong tendency to pull electrons to itself. These both form acids. Thus even in an acidic solution one sees ions like hydronium (H3O+) as the protons latch on to something.Hydrogen combines with oxygen to form water, H2O, and releases a lot of energy in

doing so, burning explosively in air. Deuterium oxide, or D2O, is commonly referred to as heavy water. Hydrogen also forms a vast array of compounds with carbon. Because of their association with living things, these compounds are called organic com-pounds, and the study of the properties of these compounds is called organic chemis-try.

Forms

Under normal conditions hydrogen gas is a mix of two different kinds of molecules which differ from one another by the relative spin of the nuclei. These two forms are known as ortho- and para-hydrogen (this is different from isotopes, see below). In ortho-hydrogen the nuclear spins are parallel (form a triplet), while in para they are antiparallel (form a singlet). At standard conditions hydrogen is composed of about 25% of the para form and 75% of the ortho form (the so-called "normal" form).


Previous Page

The equilibrium ratio of these two forms depend on temperature but since the ortho form has higher energy (is an excited state), it cannot be stable in its pure form. In low temperatures (around boiling point), the equilibrium state is comprised of almost only para form.

Isotopes

Hydrogen is the only element that has different names for its isotopes. The symbols D and T (instead of 2H and 3H) are sometimes used for deuterium and tritium, although this is not officially sanctioned. (The symbol P is already in use for phosphorus and is not available for protium.) 1H The most common isotope of hydrogen, this stable iso-tope has a nucleus consisting of a single proton; hence the descriptive, although rare-ly used, name protium. 2HThe other stable isotope is deuterium, with an extra neutron in the nucleus. Deuteri-

um comprises 0.0184-0.0082% of all hydrogen (IUPAC); ratios of deuterium to protium are reported relative to the VSMOW standard reference water. 3H The third natural-ly-occurring hydrogen isotope is the radioactive tritium. The tritium nucleus contains two neutrons in addition to the proton. 4H Hydrogen-4 was synthesised by bombard-ing tritium with fast-moving deuterium nuclei. 5H In 2001 scientists detected hydro-gen-5 by bombarding a hydrogen target with heavy ions. 6H Not yet discovered. 7H In 2003 Hydrogen-7 was created article at the RIKEN laboratory in Japan by collided a high-energy beam of helium-8 atoms with a cryogenic hydrogen target and detecting tritons-the nuclei of tritium atoms-and neutrons from the break up of Hydrogen-7, the same method used to produce and detect Hydrogen-5.

From Wikipedia, the free encyclopedia and webelements

Helium

Helium is the chemical element in the periodic table that has the symbol H, atomic number 2 and atomic weight 4.002602 It is a Noble gas element.

• Name: Helium• Symbol: He• Atomic number: 2• Atomic weight: 4.002602• Standard state: gas at 298 K• CAS Registry ID: 7440-59-7• Group in periodic table: 18• Group name: Noble gas• Period in periodic table: 1• Block in periodic table: p-block• Colour: colourless• Classification: Non-metallic

Helium is a colorless, odorless, tasteless chemical element, one of the noble gases of the periodic table of elements. Its boiling and melting points are the lowest among the elements; except in extreme conditions, it exists only as a gas. The second most abundant element in the universe, significant amounts are found on Earth only in natural gas. It is used in cryogenics, in deep-sea breathing systems, for inflating bal-loons, and as a protective gas for many purposes. Helium is not toxic and has no bio-logical effect.

Helium: Physical Properties

Melting points of the chemical elements displayed on a miniature periodic table-Melting point: 0.95 [or -272.2 °C (-458 °F)] K Boiling points of the chemical elements displayed on a miniature periodic table-

Boiling point: 4.22 [or -268.93 °C (-452.07 °F)] K Density of the chemical elements displayed on a miniature periodic tableDensity of

solid: 214 kg m-3

History


Previous Page

Helium was first detected in 1868 as a bright yellow line in the spectrum of the chro-mosphere of the Sun, by French astronomer Pierre Janssen during a solar eclipse in India. The same year, English astronomer Norman Lockyer also observed a previously unknown yellow line in the solar spectrum and concluded that it was caused by an element unknown on Earth. He and English chemist Edward Frankland named the ele-ment with the Greek word for the Sun, helios. In 1895, British chemist William Ramsay isolated helium on Earth by treating cleveite with mineral acids. These samples were identified as helium by Lockyer and British physicist William Crookes. It was inde-pendently isolated from cleveite the same year by Swedish chemists Per Teodor Cleve and Nils Langlet.In 1905, American chemists Hamilton Cady and David McFarland discovered that heli-

um could be extracted from natural gas. In 1907, Ernest Rutherford and Thomas Royds demonstrated that an alpha particle is a helium nucleus. Helium was first liquefied by Dutch physicist Heike Kamerlingh Onnes in 1908 by cooling the gas to less than one kelvin. It was first solidified in 1926 by his student Willem Hendrik Keesom. In 1938, Russian physicist Pyotr Leonidovich Kapitsa discovered that helium-4 has almost no viscosity at temperatures near absolute zero, a phenomenon now called superfluid-ity. In 1972, the same phenomenon was observed in helium-3 by American physicists Douglas D. Osheroff, David M. Lee, and Robert C. Richardson.

States

Under standard temperature and pressure, helium exists only as a monatomic gas. It solidifies only under great pressure, the variation of which can drastically change the volume of the solid. Below its boiling point of 4.21 kelvin and above the lambda point 2.1768 kelvin, the isotope helium-4 exists in a normal liquid state, called helium I. Below the lambda point, it begins to exhibit unusual characteristics, in a state called helium II. Less is known about such properties in the isotope helium-3.

Reactions

Helium is chemically unreactive under all normal conditions. With electric glow dis-charge or electron bombardment, however, helium can form compounds with tung-sten, iodine, fluorine, sulfur and phosphorus.

Isotopes

Although there are eight known isotopes of helium, only helium-3 and helium-4 are stable. The others, radioactive, rapidly decay into other substances. The most com-mon isotope, helium-4, is produced by alpha decay from heavier radioactive elements; its nucleus is an alpha particle. It is an unusually stable nucleus because its nucleons are arranged into complete shells. There is only a trace amount of helium-3 on Earth, produced from the beta decay of tritium.

Abundance

Helium is the second most abundant element in the known universe after hydrogen

and constitutes nearly a quarter of the mass of the universe. It is concentrated in the stars, where it is formed from hydrogen by the nuclear fusion of the proton-proton chain reaction and CNO cycle. According to the Big Bang model of the early develop-ment of the universe, the vast majority of helium was formed in the first three min-utes after the Big Bang.However, the concentration of helium in the Earth's atmosphere is only 1 part in

200,000, largely because most helium in the Earth's atmosphere escapes into space due to its inertness and low mass.All considerable helium on Earth is a result of radioactive decay. The decay product is

found in minerals of uranium and thorium, including cleveites, pitchblende, carnot-ite, monazite and beryl. There are also small amounts in mineral springs, volcanic gas, meteoric iron.The greatest concentrations on the planet are in natural gas, from which most com-

mercial helium is derived. The principal source in the world is the natural gas wells of the American states of Texas, Oklahoma, and Kansas.



Previous Page

Lithium

Lithium is the chemical element with symbol Li, atomic number 3 and atomic weight of 6.941. It is a Alkali metal.

• Name: Lithium• Symbol: Li• Atomic number: 3• Atomic weight: 6.941• Standard state: solid at 298 K• CAS Registry ID: 7439-93-2• Group in periodic table: 1• Group name: Alkali metal• Period in periodic table: 2• Block in periodic table: s-block• Colour: silvery white/grey• Classification: Metallic

In the periodic table, it is located in group 1, among the alkali metals. Lithium in its pure form is a soft, silver white metal, that tarnishes and oxidizes very rapidly in air and water. It is the lightest solid element and is primarily used in heat transfer alloys, in batteries and serves as a component in some drugs known as mood stabilizers.


Lithium is the lightest metal and has a density that is only half that of water. Like all alkali metals, lithium reacts easily in water and does not occur freely in nature due to its activity, nevertheless it is still less reactive than the chemically similar sodium. When placed over a flame, this metal gives off a striking crimson color but when it burns strongly, the flame becomes a brilliant white. Lithium is a univalent element.

Applications

Because of its large specific heat (the largest of any solid), lithium is used in heat transfer applications. It is also an important battery anode material due to its high electrochemical potential.

Other uses:

* Lithium salts such as lithium carbonate (Li2CO3), lithium citrate, and lithium oro-tate are mood stabilizers used in the treatment of bipolar disorder. Lithium may also have antidepressant effects. * Lithium chloride and lithium bromide are extremely hygroscopic and frequently

used as desiccants. * Lithium stearate is a common all-purpose high-temperature lubricant. * Lithium is an alloying agent used to synthesize organic compounds, and also has

nuclear applications. * Lithium is sometimes used in glasses and ceramics including the glass for the 200-

inch telescope at Mt. Palomar. * Lithium hydroxide is employed to extract carbon dioxide from the air in spacecraft

and submarines. * Alloys of the metal with aluminium, cadmium, copper, and manganese are used to

make high performance aircraft parts. * Lithium niobate is used extensively in the telecoms market, such as mobile phones

and optical modulators. * The high nonlinearity of lithium niobate also makes a good choice for nonlinear

applications.

History

Lithium (Greek lithos, meaning "stone") was discovered by Johann Arfvedson in 1817. Arfvedson found the new element within the minerals spodumene and lepidolite in a petalite ore, LiAl (Si2O5) 2, he was analyzing from the island Uto in Sweden. In 1818 Christian Gmelin was the first to observe that lithium salts give a bright red color in flame. Both men tried and failed to isolate the element from its salts, however.The element was not isolated until W.T. Brande and Sir Humphrey Davy later used

electrolysis on lithium oxide. Commercial production of lithium metal was achieved in 1923 by the German company Metallgesellschaft AG through using electrolysis of mol-ten lithium chloride and potassium chloride.It was apparently given the name "lithium" because it was discovered from a mineral

while other common alkali metals were first discovered from plant tissue.

Occurrence

Lithium is widely distributed but does not occur in nature in its free form. Because of its reactivity, it is always found bound with one or more other elements or com-pounds. It forms a minor part of almost all igneous rocks and is also found in many natural brines. Since the end of World War II, lithium production has greatly in-creased. The metal is separated from other elements in igneous rocks, and is also ex-tracted from the water of mineral springs. Lepidolite, spodumene, petalite, and am-blygonite are the more important minerals containing it.In the United States lithium is recovered from brine pools in the dry Searles Lake, in

California, and from places in Nevada and elsewhere. The metal, which is silvery in ap-pearance like sodium, potassium and other members of the alkali metal series, is pro-duced electrolytically from a mixture of fused lithium and potassium chloride. This metal cost about US$ 300 per pound in 1997.


Previous Page

Isotopes

Naturally occurring lithium is composed of 2 stable isotopes Li-6 and Li-7 with Li-7 being the most abundant (92.5% natural abundance). Six radioisotopes have been characterized with the most stable being Li-8 with a half-life of 838 ms and Li-9 with a half-life of 178.3 ms. All of the remaining radioactive isotopes have half-lifes that are less than 8.5 ms or are not known.The isotopes of lithium range in atomic weight from 4.027 amu (Li-4) to 11.0438 amu

(Li-11). The primary decay mode before the most abundant stable isotope, Li-7, is pro-ton emission (with one case of alpha decay) and the primary mode after is beta emis-sion (with some neutron emission). The primary decay products before Li-7 are ele-ment 2 (helium) isotopes and the primary products after are element 4 (beryllium) isotopes.Lithium-7 is one of the primordial elements (produced in big bang nucleosynthesis).

Lithium isotopes fractionate substantially during a wide variety of natural processes, including mineral formation (chemical precipitation), metabolism, ion exchange (Li substitutes for magnesium and iron in octahedral sites in clay minerals, where Li-6 is preferential over Li-7), hyperfiltration, and rock alteration.

F rom Wikipedia, the free encyclopedia and webelements

Beryllium

Beryllium is the chemical element in the periodic table that has the symbol Be, atom-ic number 4 and atomic weight of 9.012182 It is a Alkaline Earth Metal.

• Name: Beryllium• Symbol: Be• Atomic number: 4• Atomic weight: 9.012182• Standard state: solid at 298 K• CAS Registry ID: 7440-41-7• Group in periodic table: 2• Group name: Alkaline earth metal• Period in periodic table: 2• Block in periodic table: s-block• Colour: lead grey• Classification: Metallic

A toxic bivalent element, beryllium is a steel grey, strong, light-weight yet brittle, al-kaline earth metal, that is primarily used as a hardening agent in alloys (most notably, beryllium copper).

Notable characteristics

Beryllium has one of the highest melting points of the light metals. The modulus of elasticity of beryllium is approximately 1/3 greater than that of steel. It has excellent thermal conductivity, is nonmagnetic and resists attack by concentrated nitric acid. It is highly permeable to X-rays, and neutrons are liberated when it is hit by alpha particles, as from radium or polonium (about 30 neutrons/million alpha particles). At standard temperature and pressures beryllium resists oxidation when exposed to air (although its ability to scratch glass is probably due to the formation of a thin layer of the oxide)

Applications

Beryllium is used as an alloying agent in the production of beryllium copper. (Be has the ability to absorb large amounts of heat.) Beryllium-copper alloys are used in a wide variety of applications because of their electrical and thermal conductivity, high


Previous Page

strength and hardness, nonmagnetic properties, along with good corrosion and fa-tigue resistance. These applications include the making of: spot-welding electrodes, springs, non-sparking tools and electrical contacts.Due to their stiffness, light weight, and dimensional stability over a wide tempera-

ture range, beryllium-copper alloys are also used in the defense and aerospace indus-tries as light-weight structural materials in high-speed aircraft, missiles, space vehi-cles and communication satellites. Thin sheets of beryllium foil are used with X-ray detection diagnostics to filter out visible light and allow only X-rays to be detected.In the field of X-ray lithography beryllium is being used for the reproduction of mi-

croscopic integrated circuits. Because it has a low thermal neutron absorption cross section, the nuclear power industry uses this metal in nuclear reactors as a neutron reflector and moderator.Beryllium is also used in the making of gyroscopes, various computer equipment,

watch springs and instruments where light-weight, rigidity and dimensional stability are needed. Beryllium oxide is useful for many applications that require an excellent heat conductor, with high strength and hardness, with a very high melting point, and that acts as an electrical insulator.Beryllium compounds were once used in fluorescent lighting tubes, but this use was

discontinued because of berylliosis in the workers manufacturing the tubes (see be-low). It is expected that the James Webb Space Telescope will have a beryllium mirror. Because JWST will face a temperature of -240°Celsius (30 Kelvin), the mirror is made of beryllium, a material capable of handling extreme cold better than glass. Beryllium contracts and deforms less than glass and thus remains more uniform in such tem-peratures.

History

The name beryllium comes from the Greek beryllos, beryl. At one time beryllium was referred to as glucinium (from Greek glykys, sweet), due to the sweet taste of its salts. This element was discovered by Louis Vauquelin in 1798 as the oxide in beryl and in emeralds. Friedrich Wöhler and A. A. Bussy independently isolatated the metal in 1828 by reacting potassium on beryllium chloride.

Occurrence

Beryllium is found in 30 different minerals, the most important of which are bertran-dite, beryl, chrysoberyl, and phenacite. Precious forms of beryl are aquamarine and emerald. The most important commercial sources of beryllium and its compounds are beryl and bertrandite. Currently, most production of this metal is accomplished by reducing beryllium fluoride with magnesium metal. Beryllium metal did not become readily available until 1957.

Isotopes

Beryllium has only one stable isotope, Be-9. Cosmogenic beryllium (Be-10) is produced in the atmosphere by cosmic ray spallation of oxygen and nitrogen. Because berylli-um tends to exist in solution at pH levels less than about 5.5 (and most rainwater has a pH less than 5), it will enter into solution and be transported to the Earth's surface via

rainwater. As the precipitation quickly becomes more alkaline, Be drops out of solu-tion. Cosmogenic Be-10 thereby accumulates at the soil surface, where its relatively long half-life (1.5 million years) permits a long residence time before decaying to B-10 (boron). Be-10 and its daughter products have been used to examine soil erosion, soil formation from regolith, the development of lateritic soils, as well as variations in so-lar activity and the age of ice cores.The fact that Be-7 and Be-8 are unstable has profound cosmological consequences as

it means that elements heavier than beryllium could not be produced by nuclear fu-sion in the big bang. Moreover, the nuclear energy levels of beryllium-8 are such that carbon can be produced within stars, thus making life possible. (See triple-alpha pro-cess and big bang nucleosynthesis).

PrecautionsBeryllium ore, Beryllium and its salts are toxic substances and potentially carcino-

genic. Chronic berylliosis is a pulmonary and systemic granulomatous disease caused by exposure to beryllium. Acute beryllium disease in the form of chemical pneumo-nitis was first reported in Europe in 1933 and in the United States in 1943. Cases of chronic berylliosis were first described in 1946 among workers in plants manufactur-ing fluorescent lamps in Massachusetts. Chronic berylliosis resembles sarcoidosis in many respects, and the differential diagnosis is often difficult.Although the use of beryllium compounds in fluorescent lighting tubes was discon-

tinued in 1949, potential for exposure to beryllium exists in the nuclear and aerospace industries and in the refining of beryllium metal and melting of beryllium-containing alloys, the manufacturing of electronic devices, and the handling of other berylli-um-containing material.Early researchers tasted beryllium and its various compounds for sweetness in order

to verify its presence. Modern diagnostic equipment no longer necessitates this high-ly risky procedure and no attempt should be made to ingest this substance. Beryllium and its compounds should be handled with great care and special precautions must be taken when carrying out any activity which could result in the release of beryllium dust (lung cancer is a possible result of prolonged exposure to beryllium laden dust).This substance can be handled safely if certain procedures are followed. No attempt

should be made to work with beryllium before familiarization with correct handling procedures.



Previous Page

Boron

Boron is the chemical element in the periodic table that has the symbol B, atomic number 5 and atomic weight of 10.811. It is a Semi-metallic element..

• Name: Boron• Symbol: B• Atomic number: 5• Atomic weight: 10.811• Standard state: solid at 298 K• CAS Registry ID: 7440-42-8• Group in periodic table: 13• Group name: (none)• Period in periodic table: 2• Block in periodic table: p-block• Colour: black• Classification: Semi-metallic

A trivalent metalloid element, boron occurs abundantly in the ore borax. There are two allotropes of boron; amorphous boron is a brown powder, but metallic boron is black. The metallic form is hard (9.3 on Mohs' scale) and a bad conductor in room tem-peratures. It is never found free in nature.


Boron is electron-deficient, possessing a vacant p-orbital. Compounds of boron often behave as Lewis acids, readily bonding with electron-rich substances in an attempt to quench boron's insatiable hunger for electrons.Optical characteristics of this element include the transmittance of infrared light. At

standard temperatures boron is a poor electrical conductor but is a good conductor at high temperatures.Boron has the highest tensile strength of any known element. Boron nitride can be

used to make materials that are as hard as diamond. The nitride also acts as an elec-trical insulator but conducts heat similar to a metal. This element also has lubricating qualities that are similar to graphite. Boron is also similar to carbon with its capability to form stable covalently bonded molecular networks.

Applications

The most economically important compound of boron is sodium tetraborate decahy-drate Na2B4O7 - 10H2O, or borax, which is used in large amounts in making insulating fiberglass and sodium perborate bleach. Other uses: Because of its distinctive green color, amorphous boron is used in pyrotechnic flares. Boric acid is an important com-pound used in textile products.Compounds of boron are used extensively in organic synthesis and in the manufac-

ture of borosilicate glasses. Other compounds are used as wood preservatives, and are particularly attractive in this regard because they possess low toxicity. Boron-10 is used to assist control of nuclear reactors, a shield against radiation and in neutron detection. Boron filaments are high-strength, lightweight materials that are chiefly used for advanced aerospace structuresBoron compounds are being investigated for use in a broad range of applications,

including as components in sugar-permeable membranes, carbohydrate sensors and bioconjugates. Medicinal applications being investigated include boron neutron cap-ture therapy and drug delivery. Other boron compounds show promise in treating arthritis.Hydrides of boron are oxidized easily and liberate a considerable amount of energy. They have therefore been studied for use as possible rocket fuels.

History

Compounds of boron (Arabic Buraq from Persian Burah) have been known of for thousands of years. In early Egypt, mummification depended upon an ore known as natron, which contained borates as well as some other common salts. Borax glazes were used in China from AD 300, and boron compounds were used in glassmaking in ancient Rome.The element was not isolated until 1808 by Sir Humphry Davy, Gay-Lussac and L. J.

Thenard, to about 50% purity. These men did not recognize the substance as an ele-ment. It was Jöns Jacob Berzelius in 1824 who identified boron as an element. The first pure boron was produced by the American chemist W. Weintraub in 1909.

Occurrence

The United States and Turkey are the world's largest producers of boron. Boron does not appear in nature in elemental form but is found combined in borax, boric acid, colemanite, kernite, ulexite and borates. Boric acid is sometimes found in volcanic spring waters. Ulexite is a borate mineral that naturally has properties of fiber optics.Economically important sources are from the ore rasorite (kernite) and tincal (borax

ore) which are both found in the Mojave Desert of California (with borax being the most important source there). Turkey is another place where extensive borax deposits are found.Pure elemental boron is not easy to prepare. The earliest methods used involve re-

duction of boric oxide with metals such as magnesium or aluminium. However the product is almost always contaminated with metal borides. (The reaction is quite spectacular though.) Pure boron can be prepared reducing volatile boron halogenides with hydrogen at high temperatures. In 1997 crystalline boron (99% pure) cost about US$5 per gram and amorphous boron cost about US$2 per gram.


Previous Page

Isotopes

Boron has two naturally-occurring stable isotopes, B-11 (80.1%) and B-10 (19.9%). The mass difference results in a wide range of B-11 values in natural waters, ranging from -16 to +59. Isotopic fractionation of boron is controlled by the exchange reactions of the boron species B(OH)3 and B(OH)4. Boron isotopes are also fractionated during min-eral crystallization, during H2O phase changes in hydrothermal systems, and during hydrothermal alteration of rock. The latter effect (species preferential removal of the 10B(OH)4 ion onto clays results in solutions enriched in 11B(OH)3 may be responsible for the large 11B enrichment in seawater relative to both oceanic crust and continental crust.


Carbon

Carbon is a chemical element in the periodic table that has the symbol C, atomic number 6 and atomic weight of 12.0107. It is a Non-Metal.

• Name: Carbon• Symbol: C• Atomic number: 6• Atomic weight: 12.0107• Standard state: solid at 298 K• CAS Registry ID: 7440-44-0• Group in periodic table: 14• Group name: (none)• Period in periodic table: 2• Block in periodic table: p-block• Colour: graphite is black, diamond is colourless• Classification: Non-metallic


Carbon is a remarkable element for many reasons. Its different forms include one of the softest (graphite) and one of the hardest (diamond) substances known to man. Moreover, it has a great affinity for bonding with other small atoms, including other carbon atoms, and its small size makes it capable of forming multiple bonds. Because of these properties, carbon is known to form nearly ten million different compounds, the large majority of all chemical compounds. Carbon compounds form the basis of all life on Earth and the carbon-nitrogen cycle provides some of the energy produced by the sun and other stars.Carbon was not created in the big bang due to the fact that it needs a triple collision

of alpha particles (helium nuclei) to be produced. The universe initially expanded and cooled too fast for that to be possible. It is produced, however, in the interior of stars in the horizontal branch, where stars transform a helium core into carbon by means of the triple-alpha process.

An abundant nonmetallic, tetravalent element, carbon has several allotropic forms: * Diamonds (hardest known mineral). Binding structure: 4 electrons in 3-dimension-

al so-called sp3-orbitals * Graphite (one of the softest substances). Binding structure: 3 electrons in 2-dimen-

sional sp2-orbitals and 1 electron in s-orbitals.


Previous Page

* Covalent bound sp1 orbitals are of chemical interest only. Fullerite (fullerenes) are nanometre-scale molecules. In the simple form 60 carbon

atoms form a graphitic layer which is bent to a 3-dimensional structure, similar to a soccer ball. Lamp black consists of small graphitic areas. These areas are randomly distributed, so the whole structure is isotropic. So-called 'glassy carbon' is isotropic and as strong as glass. Unlike normal graphite, the graphitic layers are not arranged like pages in a book, but are crumpled like crumpled paper. Carbon fibers are similar to glassy carbon. Under special treatment (stretching of organic fibers and carboniza-tion) it is possible to arrange the carbon planes in direction of the fiber. Perpendicular to the fiber axis there is no orientation of the carbon planes. The result are fibers with a higher specific strength than steel.Carbon occurs in all organic life and is the basis of organic chemistry. This nonmet-

al also has the interesting chemical property of being able to bond with itself and a wide variety of other elements, forming nearly 10 million known compounds. When united with oxygen it forms carbon dioxide which is absolutely vital to plant growth. When united with hydrogen, it forms various compounds called hydrocarbons which are essential to industry in the form of fossil fuels. When combined with both oxygen and hydrogen it can form many groups of compounds including fatty acids, which are essential to life, and esters, which give flavor to many fruits. The isotope carbon-14 is commonly used in radioactive dating.

Applications

Carbon is a vital component of all known living systems, and without it life as we know it could not exist (see carbon chauvinism). The major economic use of carbon is in the form of hydrocarbons, most notably the fossil fuels methane gas and crude oil. Crude oil is used by the petrochemical industry to produce, amongst others, pe-troleum, gasoline and kerosene, through a distillation process, in so-called refineries. Crude oil forms the raw material for many synthetic substances, many of which are collectively called plastics

Other uses:* The isotope 14C, discovered February 27, 1940, is used in radiocarbon dating. * Some smoke detectors use tiny amounts of a radioactive isotope of carbon as

source of ionizing radiation (Most smoke detectors of this type use an isotope of Am-ericium) * Graphite is combined with clays to form the 'lead' used in pencils. * Diamond is used for decorative purposes, and also as drill bits and other applica-

tions making use of its hardness. * Carbon is added to iron to make steel. * Carbon is used for control rods in nuclear reactors. * Graphite carbon in a powdered, caked form is used as charcoal for cooking, art-

work and other uses. * Charcoal pills are used in medicine in pill or powder form to adsorb toxins or poi-

sons from the digestive system. The chemical and structural properties of fullerenes, in the form of carbon nanotubes, has promising potential uses in the nascent field of nanotechnology.

History

Carbon (Latin carbo meaning "charcoal") was discovered in prehistory and was known to the ancients, who manufactured it by burning organic material in insufficient ox-ygen (making charcoal). Diamonds have long been considered rare and beautiful. The last-known allotrope of carbon, fullerenes, were discovered as byproducts of molecu-lar beam experiments in the 1980s.

Allotropes

Four allotropes of carbon are known to exist: amorphous, graphite, diamond and fullerenes. The discovery of a fifth form was announced on March 22, 2004.In its amorphous form, carbon is essentially graphite but not held in a crystalline

macrostructure. It is, rather, present as a powder which is the main constituent of substances such as charcoal and lamp black (soot).At normal pressures carbon takes the form of graphite, in which each atom is bonded

to three others in a plane composed of fused hexagonal rings, just like those in aro-matic hydrocarbons. The two known forms of graphite, alpha (hexagonal) and beta (rhombohedral), both have identical physical properties, except for their crystal struc-ture. Graphites that naturally occur have been found to contain up to 30% of the beta form, when synthetically-produced graphite only contains the alpha form. The alpha form can be converted to the beta form through mechanical treatment and the beta form reverts back to the alpha form when it is heated above 1000°C.Because of the delocalization of the pi-cloud, graphite conducts electricity. The mate-

rial is soft and the sheets, frequently separated by other atoms, are held together only by van der Waals forces, so easily slip past one anotherAt very high pressures carbon has an allotrope called diamond, in which each atom

is bonded to four others. Diamond has the same cubic structure as silicon and ger-manium and, thanks to the strength of the carbon-carbon bonds, is together with the isoelectronic boron nitride (BN) the hardest substance in terms of resistance to scratching. The transition to graphite at room temperature is so slow as to be unno-ticeable. Under some conditions, carbon crystallizes as Lonsdaleite, a form similar to diamond but hexagonal.Fullerenes have a graphite-like structure, but instead of purely hexagonal packing,

also contain pentagons (or possibly heptagons) of carbon atoms, which bend the sheet into spheres, ellipses or cylinders. The properties of fullerenes (also called "bucky-balls" and "buckytubes") have not yet been fully analyzed. All the names of fullerenes are after Buckminster Fuller, developer of the geodesic dome, which mimics the struc-ture of "buckyballs". A nanofoam allotrope has been dicovered which is ferromagnetic.

Occurrence

There are nearly ten million carbon compounds that are known to science and many thousands of these are vital to life processes and very economically important organ-ic-based reactions. This element is abundant in the sun, stars, comets, and in the at-mospheres of most planets. Some meteorites contain microscopic diamonds that were formed when the solar system was still a protoplanetary disk. In combination with other elements, carbon is found the earth's atmosphere and dissolved in all bodies of water. With smaller amounts of calcium, magnesium, and iron, it is a major com-ponent of very large masses carbonate rock (limestone, dolomite, marble etc.). When


Previous Page

combined with hydrogen, carbon form coal, petroleum, and natural gas which are called hydrocarbons.Graphite is found in large quantities in New York and Texas, the United States; Russia;

Mexico; Greenland and India.Natural diamonds occur in the mineral kimberlite found in ancient volcanic "necks,"

or "pipes". Most diamond deposits are in Africa, notably in South Africa, Namibia, Bo-tswana, the Republic of the Congo and Sierra Leone. There are also deposits in Cana-da, the Russian Arctic, Brazil and in Northern and Western Australia.

Inorganic compounds

The most prominent oxide of carbon is carbon dioxide, CO2. This is a minor compo-nent of the Earth's atmosphere, produced and used by living things, and a common volatile elsewhere. In water it forms trace amounts of carbonic acid, H2CO3, but as most compounds with multiple single-bonded oxygens on a single carbon it is un-stable. Through this intermediate, though, resonance-stabilized carbonate ions are produced. Some important minerals are carbonates, notably calcite. Carbon disulfide, CS2, is similar.The other oxides are carbon monoxide, CO, and the uncommon carbon suboxide,

C3O2. Carbon monoxide is formed by incomplete combustion, and is a colorless, odor-less gas. The molecules each contain a triple bond and are fairly polar, resulting in a tendency to bind permanently to hemoglobin molecules, so that the gas is highly poisonous. Cyanide, CN-, has a similar structure and behaves a lot like a halide ion; the nitride cyanogen, (CN)2, is related.With strong metals carbon forms either carbides, C, or acetylides, C22-; these are

associated with methane and acetylene, both incredibly pathetic acids. All in all, with an electronegativity of 2.5, carbon prefers to form covalent bonds. A few carbides are covalent lattices, like carborundum, SiC, which resembles diamond.

Carbon chains

It is the atomic structure of hydrocarbons in which a series of carbon atoms, saturat-ed by hydrogen atoms, form a chain. Volatile oils have shorter chains. Fats have longer chain lengths, and waxes have extremely long chains. Carbon cycle The continuous process of combining and releasing carbon and oxygen thereby storing and emitting heat and energy. Catabolism + anabolism = metabolism. See carbon cycle.

Isotopes

Carbon has two stable, naturally-occurring isotopes: Carbon-12, or C-12, (98.89%) and Carbon-13, or C-13, (1.11%), and one unstable, naturally-occurring, radioisotope, Car-bon-14 or C-14. Ratios of these isotopes are reported inrelative to the standard VPDB (Vienna Pee Dee Belemnite from the Peedee Formation of South Carolina). The dC-13 of the atmosphere is -7. During photosynthesis, the carbon that becomes fixed in plant tissue is significantly depleted in C-13 relative to the atmosphere.There is two mode distribution in the dC-13 values of terrestrial plants resulting from

differences in the photosynthetic reaction used by the plant. Most terrestrial plants are C3 pathway plants and have dC-13 values range from -24 to -34. A second category

of plants (C4 pathway plants), composed of aquatic plants, desert plants, salt marsh plants, and tropical grasses, have dC-13 values that range from -6 to -19. An interme-diate group (CAM plants) composed of algae and lichens has dC-13 values range from -12 to -23. The dC-13 of plants and organisms can provide useful information about sources of nutrients and food web relations. In 1961 the International Union of Pure and Applied Chemistry adopted the isotope carbon-12 as the basis for atomic weights. Carbon-14 has a half-life of 5715 years and has been used extensively for radiocarbon dating wood, archaeological sites and specimens



Previous Page

Nitrogen

Nitrogen is the chemical element in the periodic table that has the symbol N, atomic number 7 and atomic weight of 14.0067. It is a Non-metallic Pnictogen.

• Name: Nitrogen• Symbol: N• Atomic number: 7• Atomic weight: 14.0067• Standard state: gas at 298 K• CAS Registry ID: 7727-37-9• Group in periodic table: 15• Group name: Pnictogen• Period in periodic table: 2• Block in periodic table: p-block• Colour: colourless• Classification: Non-metallic

A common normally colorless, odorless, tasteless and mostly inert diatomic non-met-al gas, nitrogen constitutes 78 percent of Earth's atmosphere and is a constituent of all living tissues. Nitrogen forms many important compounds such as ammonia, nitric acid, and cyanides.


Nitrogen is a non-metal, with an electronegativity of 3.0. It has five electrons in its outer shell, so is trivalent in most compounds. Pure nitrogen is an unreactive color-less diatomic gas at room temperature, and comprises about 78% of the Earth's atmo-sphere. It condenses at 77 K and freezes at 63 K. Liquid nitrogen is a common cryogen.

Applications

The greatest single commercial use of nitrogen is as a component in the manufacture of ammonia via the Haber process. Ammonia is subsequently used for fertilizer pro-duction and to produce nitric acid. Nitrogen is used as an inert atmosphere in tanks of explosive liquids, during production of electronic parts such as transistors, diodes, and integrated circuits, and is used in the manufacture of stainless steel. Nitrogen is used as a coolant both for the immersion freezing of food products and for transpor-

tation of foods, for the preservation of bodies and reproductive cells (sperm and egg), and for the stable storage of biological samples in biology.The salts of nitric acid include some important compounds, for example potassium

nitrate, or saltpeter, and ammonium nitrate. The former compound is a component of gunpowder, the latter important in fertilizer. Nitrated organic compounds, such as nitroglycerin and trinitrotoluene, are often explosives.Nitric acid is used as an oxidizer in liquid fueled rockets. Hydrazine and hydrazine de-

rivatives find use as rocket fuels. Nitrogen in its liquid state (often referred to as LN2) is often used in cryogenics. Liquid nitrogen is produced by distillation from liquid air. At atmospheric pressure, nitrogen condenses at -195.8 degrees Celsius. (-320.4 degrees Fahrenheit). It is the liquid coolant frequently used for demonstrations in science edu-cation.

History

Nitrogen (Latin nitrum, Greek Nitron meaning "native soda", "genes", "forming") is formally considered to have been discovered by Daniel Rutherford in 1772, who called it noxious air or phlogisticated air. That there was a fraction of air that did not sup-port combustion was well known to the late 18th century chemist. Nitrogen was also studied at about the same time by Carl Wilhelm Scheele, Henry Cavendish, and Joseph Priestley, who referred to it as burnt air or dephlogisticated air. Nitrogen gas was inert enough that Antoine Lavoisier referred to it as azote, which stands for without life.Compounds of nitrogen were known in the Middle Ages. The alchemists knew nitric

acid as aqua fortis. The mixture of nitric and hydrochloric acids was known as aqua regia, celebrated for its ability to dissolve gold. Nitrogen is also used in filling auto-motive tires due to its realatively flat line of thermal expansion.

Occurrence

Nitrogen is the largest single component of the Earth's atmosphere (78.1% by volume, 75.5% by weight) and is acquired for industrial purposes by the fractional distillation of liquid air. Compounds that contain this element have been observed in outer space. Nitrogen-14 is created as part of the fusion processes in stars. Nitrogen is a large com-ponent of animal waste (for example, guano), usually in the form of urea, uric acid, and compounds of these nitrogenous products.Molecular nitrogen has been known to occur in Titan's atmosphere for some time,

and has now been detected in interstellar space by David Knauth and coworkers using the Far Ultraviolet Spectroscopic Explorer.

Compounds

The main hydride of nitrogen is ammonia (NH3) although hydrazine (N2H4) is also well known. Ammonia is somewhat more basic than water, and in solution forms am-monium ions (NH4+). Liquid ammonia in fact slightly amphiprotic and forms ammo-nium and amide ions (NH2-); both amides and nitride (N3-) salts are known, but de-compose in water. Singly and doubly substituted compounds of ammonia are called amines. Larger chains, rings and structures of nitogen hydrides are also known but


Previous Page

virtually unstable.Other classes of nitrogen anions are azides (N3-), which are linear and isoelectronic to

carbon dioxide. Another molecule of the same structure is dinitrogen monoxide (N2O), or laughing gas. This is one of a variety of oxides, the most prominent of which are nitrogen monoxide (NO) and nitrogen dioxide (NO2), which both contain an unpaired electron. The latter shows some tendency to dimerize and is an important component of smog.The more standard oxides, dinitrogen trioxide (N2O3) and dinitrogen pentoxide

(N2O5), are actually fairly unstable and explosive. The corresponding acids are nitrous (HNO2) and nitric acid (HNO3), with the corresponding salts called nitrites and ni-trates. Nitric acid is one of the few acids stronger than hydronium.

Biological role

Nitrogen is an essential part of amino and nucleic acids which makes nitrogen vital to all life. Legumes like the soybean plant, can recover nitrogen directly from the atmo-sphere because their roots have nodules harboring microbes that do the actual con-version to ammonia in a process known as nitrogen fixation. The legume subsequent-ly converts ammonia to nitrogen oxides and amino acids to form proteins.

Isotopes

There are two stable isotopes: N-14 and N-15. By far the most common is N-14 (99.634%), which is produced in the CNO cycle in stars. The rest is N-15. Of the ten iso-topes produced synthetically, one has a half life of nine minutes and the remaining isotopes have half lives on the order of seconds or less. Biologically-mediated reac-tions (e.g., assimilation, nitrification, and denitrification) strongly control nitrogen dynamics in the soil. These reactions almost always result in N-15 enrichment of the substrate and depletion of the product. Although precipitation often contains sub-equal quantities of ammonium and nitrate, because ammonium is preferentially re-tained by the canopy relative to atmospheric nitrate, most of the atmospheric nitro-gen that reaches the soil surface is in the form of nitrate. Soil nitrate is preferentially assimilated by tree roots relative to soil ammonium.


Oxygen

Oxygen is the chemical element in the periodic table that has the symbol O, atomic number 8 and atomic weight of 15.9994. It is a Chalcogen a non-metallic element.

• Name: Oxygen• Symbol: O• Atomic number: 8• Atomic weight: 15.9994• Standard state: gas at 298 K• CAS Registry ID: 7782-44-7• Group in periodic table: 16• Group name: Chalcogen• Period in periodic table: 2• Block in periodic table: p-block• Colour: colourless as a gas, liquid is pale blue• Classification: Non-metallic

The element is very common, found not only on Earth but throughout the universe. Molecular oxygen (O2, often called free oxygen) on Earth is thermodynamically unsta-ble. Its initial appearance was due to the action of photosynthetic anaerobes (archaea and bacteria). Its abundance in later epochs and up to the present day has been largely driven by terrestrial plants, which release oxygen during photosynthesis.


At standard temperature and pressure, oxygen is found as a gas consisting of a di-atomic molecule, with the chemical formula O2. Oxygen is an important component of air, produced by plants during photosynthesis and is necessary for aerobic respiration in animals. The word oxygen derives from two words in Greek, oxus or oxys (acid) ge-inomai (engender). The name "oxygen" was chosen because, at the time it was discov-ered in the late 18th century, it was believed that all acids contained oxygen. It is now known that acids need not contain oxygen. Liquid O2 and solid O2 have a light blue color and both are highly paramagnetic. Liquid O2 is usually obtained by the fractional distillation of liquid air. Both liquid and solid O3 (ozone) have a deeper color of blue.Another recently discovered allotrope of oxygen, O4, is a deep red solid that is created

by pressurizing O2 to the order of 20 GPa. Its properties are being studied for use in rocket fuels and similar applications, as it is a much more powerful oxidizer than ei-ther O2 or O3.


Previous Page

Applications

Oxygen finds considerable use as an oxidizer, with only fluorine having a higher electronegativity. Liquid oxygen finds use as an oxidizer in rocket propulsion. Oxy-gen is essential to respiration, so oxygen supplementation has found use in medicine. People who climb mountains or fly in airplanes sometimes have supplemental oxygen supplies (as air). Oxygen is used in welding, and in the making of steel and methanol.Oxygen, as a mild euphoric, has a history of recreational use that extends into mod-

ern times. Oxygen bars can be seen at parties to this day. In the 19th century, oxygen was often mixed with nitrous.

History

Oxygen was discovered by the Swedish pharmacist Carl Wilhelm Scheele in 1771, but this discovery was not immediately recognized, and the independent discovery by Joseph Priestley on August 1st 1774 was more widely known. It was named by Antoine Laurent Lavoisier in 1774. The systematic element name for oxygen is octium.

Occurrence

Oxygen is the most abundant element in the Earth's crust, of which it is estimated to comprise 46.7%. Oxygen comprises about 87% by weight of the oceans (as H2O, water) and 20% of the atmosphere of Earth (as O2, molecular oxygen, or O3, ozone). Oxygen compounds, particularly metal oxides, silicates, and carbonates, are commonly found in rocks and soil. Frozen water is a common solid on the outer planets and comets. The ice caps of Mars are made of frozen carbon dioxide. Oxygen compounds are found throughout the universe and the spectrum of oxygen is often seen in stars.

Compounds

Due to its electronegativity, oxygen forms chemical bonds with almost all other ele-ments (which is the origin of the original definition of oxidation). The only elements to escape the possibility of oxidation are a few of the noble gases. The most famous of these oxides is of course hydrogen oxide, or water (H2O). Other well known exam-ples include compounds of carbon and oxygen, such as carbon dioxide (CO2), alcohols (R-OH), aldehydes, (R-CHO), and carboxylic acids (R-COOH). Oxygenated radicals such as chlorates, perchlorates, chromates, dichromates, permanganates, and nitrates are strong oxidizing agents in and of themselves. Many metals such as Iron bond with ox-ygen atoms, iron (III) oxide (Fe2O3). Ozone (O3) is formed by electrostatic discharge in the presence of molecular oxygen. A double oxygen molecule (O2)2 is known, found as a minor component of liquid oxygen. Epoxides are ethers in which the oxygen atom is part of a ring of three atoms.

Isotopes

Oxygen has three stable isotopes and ten known radioactive isotopes. The radioiso-

topes all have half lives of less than three minutes.



Previous Page

Fluorine

Fluorine (from L. Fluere, meaning "to flow"), is the chemical element in the periodic table that has the symbol F, atomic number 9 and atomic weight of 18.9984032 . It is a Non-metallic Halogen.

• Name: Fluorine• Symbol: F• Atomic number: 9• Atomic weight: 18.9984032• Standard state: gas at 298 K• CAS Registry ID: 7782-41-4• Group in periodic table: 17• Group name: Halogen• Period in periodic table: 2• Block in periodic table: p-block• Colour: pale yellow• Classification: Non-metallic

It is a poisonous pale yellow, univalent gaseous halogen that is the most chemically reactive and electronegative of all the elements. In its pure form, it is highly danger-ous, causing severe chemical burns on contact with skin.


Pure fluorine is a corrosive pale yellow gas that is a powerful oxidizing agent. It is the most reactive and electronegative of all the elements, and readily forms compounds with most other elements. Fluorine even combines with the noble gases xenon and radon. Even in dark, cool conditions, fluorine reacts explosively with hydrogen. In a jet of fluorine gas, glass, metals, water and other substances burn with a bright flame. It is far too reactive to be found in elemental form and has such an affinity for most elements, especially silicon, that it can neither be prepared nor should be kept in glass vessels. In moist air it attacks water to form the equally dangerous hydrofluoric acid.In aqueous solution, fluorine commonly occurs as the fluoride ion F-. Other forms

are fluoro-complexes (such as [FeF4]-) or H2F+. Fluorides are compounds that combine fluoride with some positively charged rest. They often consist of ions. Fluorine com-pounds with metals are among the most stable of salts.

Applications

Fluorine is used in the production of low friction plastics such as Teflon, and in ha-lons such as Freon.

Other uses:* Hydrofluoric acid (chemical formula HF) is used to etch glass in light bulbs and

other products. * Monatomic fluorine is used for plasma ashing in semiconductor manufacturing.

* Along with its compounds, fluorine is used in the production of uranium (from the hexafluoride) and in more than 100 different commercial fluorochemicals, including many high-temperature plastics. * Fluorochlorohydrocarbons are used extensively in air conditioning and in refriger-

ation. Chlorofluorocarbons have been banned for these applications because they are suspected to contribute to the ozone hole. Sulfurhexafluoride is an extremely inert and (unusually for a fluorine compound) nontoxic gas. These classes of compounds are potent greenhouse gases. * Potassium hexafluoroaluminate, the so-called cryolite, is used in electrolysis of

aluminium. * Sodium fluoride has been used as an insecticide, especially against cockroaches. * Some other fluorides are often added to toothpaste and (somewhat controver-

sially) to municipal water supplies to prevent dental cavities. Some researchers - in-cluding US space scientists in the early 1960s have studied elemental fluorine gas a possible rocket propellant due to its exceptionally high specific impulse. Experiments failed since fluorine was so hard to handle

History

Fluorine (L fluere meaning flow or flux) in the form of fluorspar (calcium fluoride) was described in 1529 by Georigius Agricola for its use as a flux, which is a substance that is used to promote the fusion of metals or minerals. In 1670 Schwandhard found that glass was etched when it was exposed to fluorspar that was treated with acid. Karl Scheele and many later researchers, including Humphry Davy, Gay-Lussac, An-toine Lavoisier, and Louis Thenard all would experiment with hydrofluoric acid, eas-ily obtained by treating calcium fluoride (fluorspar) with concentrated sulfuric acid. It was eventually realised that hydrofluoric acid contained a previously unknown element. This element was not isolated for many years after this due to its extreme reactivity - it is separated from its compounds only with difficulty and then it im-mediately attacks the remaining materials of the compound. Finally in 1886 fluorine was isolated by Henri Moissan after almost 74 years of continuous effort. It was an effort which cost several researchers their health or even their lives, and for Moissan, it earned him the 1906 Nobel Prize in chemistry. The first commercial production of fluorine was needed for the atomic bomb Manhattan project in World War II where the compound uranium hexafluoride (UF6) was used to separate the U-235 and U-238 isotopes of uranium. Today both the gaseous diffusion process and the gas centrifuge process use gaseous (UF6) to produce enriched uranium for nuclear power applica-tions.


Previous Page

From Wikipedia, the free encyclopedia and webelements Neon

Neon is the chemical element in the periodic table that has the symbol Ne, atomic number 10 and atomic weight of 20.1797. It is a Nobel Gas.

• Name: Neon• Symbol: Ne• Atomic number: 10• Atomic weight: 20.1797• Standard state: gas at 298 K• CAS Registry ID: 7440-01-9• Group in periodic table: 18• Group name: Noble gas• Period in periodic table: 2• Block in periodic table: p-block• Colour: colourless• Classification: Non-metallic

A colorless nearly inert noble gas, neon gives a distinct reddish glow when used in vacuum discharge tubes and neon lamps and is found in air in trace amounts.


Neon is the second-lightest noble gas, glows reddish-orange in a vacuum discharge tube and has over 40 times the refrigerating capacity of liquid helium and three times that of liquid hydrogen (on a per unit volume basis). In most applications it is a less expensive refrigerant than helium. Neon has the most intense discharge at normal voltages and currents of all the rare gases.

Applications

The reddish-orange color that neon emits in neon lights is widely used to make advertising signs. "Neon" is also used generically for these types of lights when in reality many other gases are used to produce different colors of light. Other uses: * High-voltage indicators. * Lightning arrestors. * Wave meter tubes. * Television tubes. * Neon and helium are used to make a type of gas laser. Liquefied neon is com-mercially used as an economical cryogenic refrigerant.


Previous Page

History

Neon (Greek neos meaning "new") was discovered by William Ramsay and Morris Tra-vers in 1898.

Occurrence

Neon is usually found in the form of a gas with molecules consisting of a single neon atom. Neon is a rare gas that is found in the Earth's atmosphere at 1 part in 65,000 and is produced by supercooling air and fractionally distilling it from the resulting cryo-genic liquid.

Compounds

Even though neon is for most practical purposes an inert element, it can form an exotic compound with fluorine in the laboratory. It is not known for certain if this or any neon compound exists naturally but some evidence suggests that this may be true. The ions, Ne+, (NeAr)+, (NeH)+, and (HeNe+) are have also been observed from op-tical and mass spectrometric research. In addition, neon forms an unstable hydrate.

Isotopes

Neon has three stable isotopes: Ne-20 (90.48%), Ne-21 (0.27%) and Ne-22 (9.25%). Ne-21 and Ne-22 are nucleogenic and their variations are well understood. In contrast, Ne-20 is not known to be nucleogenic and the causes of its variation in the Earth have been hotly debated. The principal nuclear reactions which generate neon isotopes are neu-tron emission, alpha decay reactions on Mg-24 and Mg-25, which produce Ne-21 and Ne-22, respectively. The alpha particles are derived from uranium-series decay chains, while the neutrons are mostly produced by secondary reactions from alpha particles. The net result yields a trend towards lower Ne-20/Ne-22 and higher Ne-21/Ne-22 ratios observed in uranium-rich rocks such as granites. Isotopic analysis of exposed terres-trial rocks has demonstrated the cosmogenic production of Ne-21. This isotope is gen-erated by spallation reactions on Mg, Na, Si and Al. By analyzing all three isotopes, the cosmogenic component can be resolved from magmatic neon and nucleogenic neon. This suggests that neon will be a useful tool in determining cosmic exposure ages of surficial rocks and meteorites.Similar to xenon, neon contents observed in samples of volcanic gases are enriched in

Ne-20, as well as nucleogenic Ne-21, relative to Ne-22 contents. The neon isotopic con-tents of these mantle-derived samples represent a non-atmospheric source of neon. The Ne-20-enriched components were attributed to exotic primordial rare gas compo-nents in the Earth, possibly representing solar neon. Elevated Ne-20 abundances were also found in diamonds, further suggesting a solar neon reservoir in the Earth.



Previous Page

Sodium

Sodium is the chemical element in the periodic table that has the symbol Na, (Natri-um in Latin) atomc number 11 and atomic weight 22.98976928. It is a Alkali metal.

• Name: Sodium• Symbol: Na• Atomic number: 11• Atomic weight: 22.98976928• Standard state: solid at 298 K• CAS Registry ID: 7440-23-5• Group in periodic table: 1• Group name: Alkali metal• Period in periodic table: 3• Block in periodic table: s-block• Colour: silvery white• Classification: Metallic

Sodium is a soft, waxy, silvery reactive metal belonging to the alkali metals that is abundant in natural compounds (especially halite). It is highly reactive, burns with a yellow flame, oxidizes in air and reacts violently with water, forcing it to be kept un-der oil.


Like the other alkali metals, sodium is a soft, light-weight, silvery white, reactive element that is never found unbound in nature. Sodium floats in water, as well as decomposing it to release hydrogen and thus is formed hydroxide. If ground to a fine enough powder, sodium will ignite spontaneously in water. However, this metal does not normally ignite in air below 388 kelvin.

Applications

Sodium in its metallic form is an essential component in the making of esters and in the manufacture of organic compounds. This alkali metal is also a component of sodi-um chloride (NaCl) which is vital to life.

Other uses:

* In certain alloys to improve their structure, * In soap (in combination with fatty acids), * To descale metal.(make its surface smooth) * To purify molten metals. * In sodium vapor lamps, an efficient means of producing light from electricity. NaK,

an alloy of sodium and potassium, is an important heat transfer material.

History

Sodium (English, soda) has long been recognized in compounds, but was not isolated until 1807 by Sir Humphry Davy through the electrolysis of caustic soda. In medieval Europe a compound of sodium with the Latin name of sodanum was used as a head-ache remedy. Sodium's symbol, Na, comes for the neo-Latin name for a common sodi-um compound named natrium, which comes from the Greek nÃ tron, a kind of natural salt.

Occurrence

Sodium is relatively abundant in stars and the D spectral lines of this element are among the most prominent in star light. Sodium makes up about 2.6% of the Earth's crust making it the fourth most abundant element overall and the most abundant alkali metal. It is now produced commercially through the electrolysis of completely dry fused sodium chloride. This method is less expensive than the previous method of electrolyzing sodium hydroxide. Metallic sodium cost about 15 to 20 US cents per pound in 1997 but reagent grade (ACS) sodium cost about US$35 per pound in 1990. It is the cheapest of all metals by volume.

Compounds

Sodium chloride, better known as common salt, is the most common compound of sodium, but sodium occurs in many other minerals, such as amphibole, cryolite, ha-lite, soda niter, zeolite, etc. Sodium compounds are important to the chemical, glass, metal, paper, petroleum, soap, and textile industries. Soap is generally a sodium salt of certain fatty acids.The sodium compounds that are the most important to industry are common salt

(NaCl), soda ash (Na2CO3), baking soda (NaHCO3), caustic soda (NaOH), Chile saltpeter (NaNO3), di- and tri-sodium phosphates, sodium thiosulfate (hypo, Na2S2O3 5H2O), and borax (Na2B4O7 10H2O).

Isotopes

There are thirteen isotopes of sodium that have been recognized. The only stable iso-tope is Na-23. Sodium has two radioactive cosmogenic isotopes (Na-22, half-life = 2.605 years; Na-24, half-life = ~ 15 hours).


Previous Page

From Wikipedia, the free encyclopedia and webelements Magnesium

Magnesium is the chemical element in the periodic table that has the symbol Mg, atomic number 12 and atomic weigh of 24.3050. It is a Alkaline Earth Metal.

• Name: Magnesium• Symbol: Mg• Atomic number: 12• Atomic weight: 24.3050• Standard state: solid at 298 K• CAS Registry ID: 7439-95-4• Group in periodic table: 2• Group name: Alkaline earth metal• Period in periodic table: 3• Block in periodic table: s-block• Colour: silvery white

Classification: Metallic Magnesium is the eighth most abundant element and con-stitutes about 2% of the Earth's crust, and it is the third most plentiful element dis-solved in seawater. This alkaline earth metal is primarily used as an alloying agent to make aluminium-magnesium alloys..


Magnesium is a fairly strong, silvery-white, light-weight metal (one third lighter than aluminium) that slightly tarnishes when exposed to air. In a powder, this metal heats and ignites when exposed to air and burns with a white flame. It is difficult to ignite in bulk, though it is easy to light if it is shaved into thin strips. Once ignited, it is dif-ficult to extinguish, being able to burn in both nitrogen (forming magnesium nitride), and carbon dioxide.

Uses

Magnesium compounds, primarily magnesium oxide, are used mainly as refractory material in furnace linings for producing iron and steel, nonferrous metals, glass, and cement. Magnesium oxide and other compounds also are used in agricultural, chemi-cal, and construction industries. This element's principal use is as an alloying additive to aluminium with these aluminium-magnesium alloys being used mainly for bever-


Previous Page

age cans. Magnesium alloys also are used as structural components of automobiles and machinery. Another use of this metal is to aid the removal of sulfur from iron and steel. Other uses include: * Magnesium, like aluminium, is strong and light, so it is often used in high grade

car wheels, called "mag wheels.* Combined in alloys this metal is essential for airplane and missile construction. * When used as an alloying agent, this metal improves the mechanical, fabrication,

and welding characteristics of aluminium. * Additive agent for conventional propellants and used in producing nodular graph-

ite in cast iron. * Reducing agent for the production of pure uranium and other metals from their

salts. * Its hydroxide is used in milk of magnesia, its chloride and sulfate in Epsom salts,

and its citrates are used in medicine. * Dead-burned magnesite is used for refractory purposes such as brick and liners in

furnaces and converters. * Magnesium is also flammable, burning at a temperature of approximately 4000°F. * The extremely high temperature at which magnesium burns makes it a handy tool

for starting emergency fires during outdoor recreation. * Magnesium carbonate (MgCO3) powder is also used by athletes, such as gymnasts

and weightlifters, to improve the grip on objectsâ€”the apparatus or lifting bar. * Other uses include flashlight photography, flares, and pyrotechnics, including in-

cendiary bombs..

History

The name originates from the Greek word for a district in Thessaly called Magnesia. Joseph Black in England recognized magnesium as being an element in 1755, Sir Hum-phrey Davey electrolytically isolated pure magnesium metal in 1808 from a mix of magnesia and HgO and A. A. B. Bussy prepared it in coherent form in 1831. Magnesium is the eighth most abundant element in the earth's crust. It is an alkaline earth met-al and therefore does not occur uncombined with other elements. It is found in large deposits of magnesite, dolomite, and other minerals.

Sources

In the United States this metal is principally obtained by electrolysis of fused magne-sium chloride from brines, wells, and sea water. Although magnesium is found in over 60 minerals, only dolomite, magnesite, brucite, carnallite, talc, and olivine are of com-mercial importance.Compounds in living organismsOrganic magnesium is important in both plant and animal life. Chlorophylls are mag-

nesium-centered porphyrins. The adult daily nutritional requirement, which is affect-ed by various factors including gender, weight and size, is 300-400 mg/day. Many en-zymes require the presence of magnesium ions for their catalytic action. Inadequate magnesium intake frequently causes muscle spasms, and has been associated with cardiovascular disease, diabetes, high blood pressure and osteoporosis.

Food sources

Green vegetables such as spinach provide magnesium because the center of the chlo-rophyll molecule contains magnesium. Nuts, seeds, and some whole grains are also good sources of magnesium.Although magnesium is present in many foods, it usually occurs in small amounts.

As with most nutrients, daily needs for magnesium cannot be met from a single food. Eating a wide variety of foods, including five servings of fruits and vegetables daily and plenty of whole grains, helps to ensure an adequate intake of magnesium.The magnesium content of refined foods is usually low. Whole-wheat bread, for ex-

ample, has twice as much magnesium as white bread because the magnesium-rich germ and bran are removed when white flour is processed. The table of food sources of magnesium suggests many dietary sources of magnesium. Water can provide mag-nesium, but the amount varies according to the water supply. "Hard" water contains more magnesium than "soft" water. Dietary surveys do not estimate magnesium in-take from water, which may lead to underestimating total magnesium intake and its variability.Following are some foods and the amount of magnesium in them: * spinach (1/2 cup) = 80 milligrams (mg) * peanut butter (2 tablespoons) = 50 mg * black-eyed peas (1/2 cup) = 45 mg * milk, low fat (1 cup) = 40 mg

Isotopes

Magnesium-26 is a stable isotope that has found application in isotopic geology, sim-ilar to that of aluminium. Mg-26 is a radiogenic daughter product of Al-26, which has a half-life of 717,000 years. Large enrichments of stable Mg-26 have been observed in the Ca-Al-rich inclusions of some carbonaceous chondrite meteorites. The anomalous abundance of Mg-26 is attributed to the decay of its parent Al-26 in the inclusions. Therefore, the meteorite must have formed in the solar nebula before the Al-26 had decayed. Hence, these fragments are among the oldest objects in the solar system and have preserved information about its earliest history.It is conventional to plot Mg-26/Mg-24 against an Al/Mg ratio. In an isochrone plot,

the Al/Mg ratio plotted is Al-27/Mg-24. The slope of the isochron has no age signif-icance, but indicates the initial Al-26/Al-27 ratio in the sample at the time when the systems were separated from a common reservoir.



Previous Page

Aluminium

Aluminium (or aluminum in North American English) is the chemical element in the periodic table with the symbol Al, atomic number 13, and atomic weight of 26.98154. It is a Metallic element.

• Name: Aluminium• Symbol: Al• Atomic number: 13• Atomic weight: 26.9815386 (8)• Standard state: solid at 298 K• CAS Registry ID: 7429-90-5• Group in periodic table: 13• Group name: (none)• Period in periodic table: 3• Block in periodic table: p-block• Colour: silvery• Classification: Metallic

A silvery and ductile member of the poor metal group of elements, aluminium is found primarily as the ore bauxite and is remarkable for its resistance to oxidation (al-uminium is actually almost always already oxidized, but is usable in this form unlike most metals), its strength, and its light weight. Aluminium is used in many industries to make millions of different products and is very important to the world economy. Structural components made from aluminium are vital to the aerospace industry and very important in other areas of transportation and building in which light weight, durability, and strength are needed.


Aluminium is a soft and lightweight but strong metal with a dull silver-gray appear-ance, due to a thin layer of oxidation that forms quickly when it is exposed to air and which prevents further corrosion. Aluminium is about one-third as dense as steel or copper; is malleable, ductile, and easily machined and cast; and has excellent corro-sion resistance and durability. It is also nonmagnetic and nonsparking and is the sec-ond most malleable metal (behind gold) and the sixth most ductile.

Applications

Whether measured in terms of quantity or value, the use of aluminium exceeds that of any other metal except iron, and it is important in virtually all segments of the world economy. Pure aluminium is soft and weak, but it can form alloys with small amounts of copper, magnesium, manganese, silicon, and other elements to make al-loys having a variety of useful properties. These alloys form vital components of air-craft and rockets. When aluminium is evaporated in a vacuum it forms a coating that reflects both visible light and radiant heat. These coatings form a thin layer of pro-tective aluminium oxide that does not deteriorate as silver coatings do. Coating tele-scope mirrors is another use of this metal. Some of the many uses for aluminium are in Transportation (automobiles, airplanes, trucks, railcars, marine vessels, etc.), Pack-aging (cans, foil, etc.), Machinery, Water treatment, Construction (windows, doors, siding, etc. however it has fallen out of favor for end-user wiring Consumer durable goods (appliances, cooking utensils, etc.)Electrical transmission lines (although its electrical conductivity is only 60% of cop-

per, it's lighter in weight and lower in priceDespite its usual magnetically resistant nature, it is used in MKM steel and Alnico

magnets. Super Purity Aluminium (SPA, 99.980%-99.999% Al) is used in electronics and CDs. Its oxide, alumina, is found naturally as corundum, emery, ruby, and sapphire and is used in glass making. Synthetic ruby and sapphire are used in lasers for the production of coherent light. Aluminium oxidizes very energetically and as a result has found use in solid rocket fuels and thermite.

History

The oldest suspected (although unprovable) reference to aluminium is in Pliny the Elder's Naturalis Historia: One day a goldsmith in Rome was allowed to show the Em-peror Tiberius a dinner plate of a new metal. The plate was very light, and almost as bright as silver. The goldsmith told the Emperor that he had made the metal from plain clay. He also assured the Emperor that only he, himself, and the Gods knew how to produce this metal from clay. The Emperor became very interested, and as a finan-cial expert he was also a little concerned. The Emperor felt immediately, however, that all his treasures of gold and silver would fall in value if people started to produce this bright metal of clay. Therefore, instead of giving the goldsmith the regard expected, he ordered him to be beheaded.Ancient Greeks and Romans used salts of this metal as dyeing mordants and as astrin-

gents to bind wounds, and alum is still used as a styptic. In 1761 Guyton de Morveau proposed calling the base alum alumine. In 1808, Humphry Davy identified the exis-tence of a metal base of alum, which he named (see Spelling below for more informa-tion on the name).Friedrich Wöhler is generally credited with isolating aluminium (Latin alumen, alum)

in 1827. However, this metal was produced for the first time in impure form two years earlier by Danish physicist and chemist Hans Christian Ørsted.Charles Martin Hall received the patent (400655) in 1886, on electrolytic process to ex-

tract aluminium. Henri Saint-Claire Deville (France) improved Wöhler's method (1846) and presented these in a book in 1859 with two improvements to the process as to sub-stitute potassium to sodium and double instead of simple chlorure. The invention of the Hall-Héroult process in 1886 made extracting aluminium from minerals inexpen-sive, and so it is now in common use throughout the world.


Previous Page

Occurrence and Resources

Although Al is an abundant element in Earth's crust (8.1%), it is very rare in its free form and was once considered a precious metal more valuable than gold (It is said that Napoleon III of France had a set of aluminium plates reserved for his finest guests. Others had to make do with gold ones). It is therefore comparatively new as an indus-trial metal and has been produced in commercial quantities for just over 100 years.Aluminium was, when it was first discovered, extremely difficult to separate from the

rocks it was part of. Since the whole of Earth's aluminium was bound up in the form of compounds, it was the most difficult metal on earth to get, despite the fact that it is one of the planet's most common.Recovery of this metal from scrap (via recycling) has become an important compo-

nent of the aluminium industry. Recycling involves simply melting the metal, which is far less expensive than creating it from ore. Refining aluminium requires enormous amounts of electricity; recycling it requires only 5% of the energy to produce it. A common practice since the early 1900s, aluminium recycling is not new. It was, how-ever, a low-profile activity until the late 1960s when the exploding popularity of alu-minium beverage cans finally placed recycling into the public consciousness. Sources for recycled aluminium include automobiles, windows and doors, appliances, contain-ers and other products.Aluminium is a reactive metal and cannot be extracted from its ore, bauxite (Al2O3),

through reduction with carbon. Instead it is extracted by electrolysis - the metal is oxidized in solution and then reduced again to the pure metal. The ore must be in a liquid state for this to occur. However, bauxite has a melting point of 2000°C, which is too high a temperature to achieve economically. Instead, the bauxite for many years was dissolved in molten cryolite, which lowers the melting point to about 900°C. But now, cryolite has been replaced by an artificial mixture of aluminium, sodium, and calcium fluorides. This process still requires a great deal of energy, and aluminium plants usually have their own power stations nearby.The electrodes used in the electrolysis of bauxite are both carbon. Once the ore is in

the molten state, its ions are free to move around. Here the aluminium ion is being reduced (electrons are added). The aluminium metal then sinks to the bottom and is tapped off. The positive anode oxidizes the oxygen of bauxite, to form oxygen gas. This cathode must be replaced often because the oxygen gas formed is extremely hot, and eats away the carbon electrode in the following reaction.Despite the cost of elec-trolysis, aluminium is a very widely used metal. Aluminium can now be extracted from clay, but this process is not economical.Electric power represents about a third of the cost of refining aluminium. For this

reason, refineries tend to be located where electric power is plentiful and inexpen-sive, such as the United States Pacific Northwest, the South Island of New Zealand, and Quebec in Canada. China is currently (2004) the top world producer of aluminium.

Isotopes

Aluminium has nine isotopes, whose mass numbers range from 23 to 30. Only Al-27 (stable isotope) and Al-26 (radioactive isotope, t1/2 = 7.2 * 105 y) occur naturally. Al-26 is produced from argon in the atmosphere by spallation caused by cosmic-ray pro-tons. Aluminium isotopes have found practical application in dating marine sedi-ments, manganese nodules, glacial ice, quartz in rock exposures, and meteorites. The

ratio of Al-26 to beryllium-10 has been used to study the role of transport, deposition, sediment storage, burial times, and erosion on 105 to 106 year time scales. Cosmogenic Al-26 was first applied in studies of the Moon and meteorites. Meteorite fragments, after departure from their parent bodies, are exposed to intense cosmic-ray bombard-ment during their travel through space, causing substantial Al-26 production. After falling to Earth, atmospheric shielding protects the meteorite fragments from further Al-26 production, and its decay can then be used to determine the meteorite's terres-trial age. Meteorite research has also shown that Al-26 was relatively abundant at the time of formation of our planetary system. Possibly, the energy released by the decay of Al-26 was responsible for the remelting and differentiation of some asteroids after their formation 4.6 billion years ago.



Previous Page

Silicon

Silicon is the chemical element in the periodic table that has the symbol Si. atomic number 14 and atomic weight of 28.0855. It is a Semi metallic element.

• Name: Silicon• Symbol: Si• Atomic number: 14• Atomic weight: 28.0855• Standard state: solid at 298 K• CAS Registry ID: 7440-21-3• Group in periodic table: 14• Group name: (none)• Period in periodic table: 3• Block in periodic table: p-block• Colour: dark grey with a bluish tinge• Classification: Semi-metallic

A tetravalent metalloid, silicon is less reactive than its chemical analog carbon. It is the second most abundant element in the Earth's crust, making up 25.7% of it by weight. It occurs in clay, feldspar, granite, quartz and sand, mainly in the form of sili-con dioxide (also known as silica) and silicates (compounds containing silicon, oxygen and metals). Silicon is the principal component of glass, cement, ceramics, most semi-conductor devices, and silicones, the latter a plastic substance often confused with silicon.


In its crystalline form, silicon has a metallic luster and a grayish color. Even though it is a relatively inert element, silicon still reacts with halogens and dilute alkalis, but most acids (except for a combination of nitric acid and hydrofluoric acid) do not affect it. Elemental silicon transmits more than 95% of all wavelengths of infrared light. Pure silicon crystals are rarely found in nature, as natural silicon is usually found as silica (SiO2). Pure silicon crystals can be found as inclusions in gold, or in volcanic exhala-tions.ApplicationsSilicon is a very useful element that is vital to many human industries. Silicon diox-

ide in the form of sand and clay is an important ingredient of concrete and brick and is also used to produce Portland cement. Silicon is a very important element for plant

and animal life. Diatoms extract silica from water to build their protective cell walls.

Other uses: * Pottery/Enamel - It is a refractory material used in high-temperature material pro-

duction and its silicates are used in making enamels and pottery. * Steel - Silicon is an important constituent of some steels. * Glass - Silica from sand is a principal component of glass. Glass can be made into a

great variety of shapes and is used to make window glass, containers, and insulators, among many other uses. * Abrasives - Silicon carbide is one of the most important abrasives. * Semiconduc-

tor - Ultrapure silicon can be doped with arsenic, boron, gallium, or phosphorus to make silicon more conductive for use in transistors, solar cells and other semiconduc-tor devices which are used in electronics and other high-tech applications. * Photonics - Silicon can be used in lasers to produce coherent light with a wave-

length of 456 nm. * Medical materials - Silicones are flexible compounds containing silicon-oxygen

and silicon-carbon bonds; they are widely used in applications such as artificial breast implants and contact lenses. * LCDs and solar cells - Hydrogenated amorphous sil-icon has shown promise in the production of low-cost, large-area electronics in ap-plications such as LCDs. It has also shown promise for large-area, low-cost solar cells. * Construction - Silica is a major ingredient in bricks because of its low chemical activity.

History

Silicon (Latin silex, silicis meaning flint) was first identified by Antoine Lavoisier in 1787, and was later mistaken by Humphry Davy in 1800 for a compound. In 1811 Gay Lus-sac and Thénard probably prepared impure amorphous silicon through the heating of potassium with silicon tetrafluoride. In 1824 Berzelius prepared amorphous silicon using approximately the same method of Lussac. Berzelius also purified the product by repeatedly washing it.Because silicon is an important element in semiconductor and high-tech devices, the

high-tech region of Silicon Valley, California, is named after this element.

Occurrence

Silicon is a principal component of aerolites which are a class of meteoroids and also of tektites which is a natural form of glass.Measured by weight, silicon makes up 25.7% of the earth's crust and after oxygen is

also the second most abundant element. Elemental silicon is not found in nature. It occurs most often as oxides and as silicates. Sand, amethyst, agate, quartz, rock crys-tal, flint, jasper, and opal are some of the forms in which the oxide appears. Granite, asbestos, feldspar, clay, hornblende, and mica are a few of the many silicate minerals.

Production

Silicon is commercially prepared by the heating of high-purity silica in an electric arc furnace using carbon electrodes. At temperatures over 1900°C, the carbon reduces the


Previous Page

silica to silicon according to the chemical equation SiO2 + C Si + CO2 Liquid silicon collects in the bottom of the furnace, and is then drained and cooled. The silicon pro-duced via this process is called metallurgical grade silicon and is at least 99% pure. In 1997, metallurgical grade silicon cost about $ 0.50 per gm in 2000, silicon metal (99% pure silicon) averaged 56 cents per pound .

Purification

The use of silicon in semiconductor devices demands a much greater purity than afforded by metallurgical grade silicon. Historically, a number of methods have been used to produce high-purity silicon.Physical methodsEarly silicon purification techniques were based on the fact that if silicon is melted

and re-solidified, the last parts of the mass to solidify contain most of the impurities. The earliest method of silicon purification, first described in 1919 and used on a limit-ed basis to make radar components during World War II, involved crushing metallur-gical grade silicon and then partially dissolving the silicon powder in an acid. When crushed, the silicon cracked so that the weaker impurity-rich regions were on the outside of the resulting grains of silicon. As a result, the impurity-rich silicon was the first to be dissolved when treated with acid, leaving behind a more pure product.In zone melting, the first silicon purification method to be widely used industrially,

rods of metallurgical grade silicon are heated to melt at one end. Then, the heater is slowly moved down the length of the rod, keeping a small length of the rod molten as the silicon cools and resolidifies behind it. Since most impurities tend to remain in the molten region rather than resolidify, when the process is complete, most of the impu-rities in the rod will have been moved into the end that was the last to be melted. This end is then cut off and discarded, and the process repeated if a still higher purity was desired.

Chemical methods

Today, silicon is instead purified by converting it to a silicon compound that can be more easily purified than silicon itself, and then converting that silicon compound back into pure silicon. Trichlorosilane is the silicon compound most commonly used as the intermediate, although silicon tetrachloride and silane are also used. When these gases are blown over silicon at high temperature, they decompose to high-purity sili-con.In the Siemens process, high-purity silicon rods are exposed to trichlorosilane at

1150°C. The trichlorosilane gas decomposes and deposits additional silicon onto the rods, enlarging them according to chemical reactions like 2 HSiCl3 Si + 2 HCl + SiCl4 Silicon produced from this and similar processes is called polycrystalline silicon. Poly-crystalline silicon typically has impurity levels of 1 part per billion or less. At one time, DuPont produced ultrapure silicon by reacting silicon tetrachloride with high-purity zinc vapors at 950Â°C, producing silicon according to the chemical equation SiCl4 + 2 Zn Si + 2 ZnCl2 However, this technique was plagued with practical problems (such as the zinc chloride byproduct solidifying and clogging lines) and was eventually aban-doned in favor of the Siemens process.

Crystallization

The Czochralski process is often used to make high-purity single silicon crystals for use in solid-state semiconductor devices.IsotopesSilicon has nine isotopes, with mass numbers from 25-33. Si-28 (the most abundant

isotope, at 92.23%), Si-29 (4.67%), and Si-30 (3.1%) are stable; Si-32 is a radioactive iso-tope produced by argon decay. Its half-life, after much argument, has been deter-mined to be approximately 276 years, and it decays by beta emission to P-32 (which has a 14.28 year half-life) and then to S-32.



Previous Page

Phosphorus

Phosphorus is the chemical element in the periodic table that has the symbol P, atom-ic number 15 and atomic weight of 30.973762. It is a Non-metallic Pnictogen.

• Name: Phosphorus• Symbol: P• Atomic number: 15• Atomic weight: 30.973762• Standard state: solid at 298 K• CAS Registry ID: 7723-14-0• Group in periodic table: 15• Group name: Pnictogen• Period in periodic table: 3• Block in periodic table: p-block• Colour: colourless/red/silvery white• Classification: Non-metallic

A multivalent, nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate rocks and in all living cells but is never naturally found alone. It is highly reactive, emits a faint glow upon uniting with oxygen (hence its name, Lat-in for 'morning star', from Greek words meaning 'light' and 'bring'), occurs in several forms, and is an essential element for living organisms. The most important use of phosphorus is in the production of fertilizers. It is also widely used in explosives, fric-tion matches, fireworks, pesticides, toothpaste, and detergents.


Common phosphorus forms a waxy white solid that has a characteristic disagreeable smell but when it is pure it is colorless and transparent. This non metal is not soluble in water, but it is soluble in carbon disulfide. Pure phosphorus ignites spontaneously in air and burns to phosphorus pentoxide.

Forms

Phosphorus exists in four or more allotropic forms: white (or yellow), red, and black (or violet). The most common are red and white phosphorus, both of which are tet-rahedral groups of four atoms. White phosphorus burns on contact with air and, on

exposure to heat or light, it can transform into red phosphorus. It also exists in two modifications: alpha and beta which are separated by a transition temperature of -3.8°C. Red phosphorus is comparatively stable and sublimes at a vapor pressure of 1 atm at 170 °C but burns from impact or frictional heating. A black phosphorus allo-trope exists which has a structure similar to graphite - the atoms are arranged in hex-agonal sheet layers and will conduct electricity.

Applications

Concentrated phosphoric acids, which can consist of 70% to 75% P2O5 are very im-portant to agriculture and farm production in the form of fertilizers. Global demand for fertilizers has led to large increases in phosphate production in the second half of the 20th century.

Other uses:

* Phosphates are utilized in the making of special glasses that are used for sodium lamps. * Bone-ash, calcium phosphate, is used in the production of fine china and to make

mono-calcium phosphate which is employed in baking powder. * This element is also an important component in steel production, in the making of

phosphor bronze, and in many other related products. * Trisodium phosphate is widely used in cleaning agents to soften water and for pre-

venting pipe/boiler tube corrosion. * White phosphorus is used in military applications as incendiary bombs, smoke

pots, smoke bombs and tracer bullets. * Miscellaneous uses; used in the making of safety matches, pyrotechnics, pesticides,

toothpaste, detergents, etc.

Biological role

Phosphorus compounds perform vital functions in all known forms of life. Inorgan-ic phosphorus plays a key role in biological molecules such as DNA and RNA where it forms part of those molecules' molecular backbones. Living cells also utilize inorganic phosphorus to store and transport cellular energy via adenosine triphosphate (ATP). Calcium phosphate salts are used by animals to stiffen bones and phosphorus is also an important element in cell protoplasm and nervous tissue.

History

Phosphorus (Greek. phosphoros, meaning "light bearer" which was the ancient name for the planet Venus) was discovered by German alchemist Hennig Brand in 1669 through a preparation from urine. Working in Hamburg, Brand attempted to distill salts by evaporating urine, and in the process produced a white material that glowed in the dark and burned brilliantly. Since that time, phosphorescence has been used to describe substances that shine in the dark without burning.Early matches used white phosphorus in their composition, which was dangerous

due to its toxicity. Murders, suicides and accidental poisonings resulted from its use


Previous Page

(An apocryphal tale tells of a woman attempting to murder her husband with white phosphorus in his food, which was detected by the stew giving off luminous steam). In addition, exposure to the vapors gave match workers a necrosis of the bones of the jaw, the infamous "phossy-jaw." When red phosphorus was discovered, with its far lower flammability and toxicity, it was adopted as a safer alternative for match manu-facture.

Occurrence

Due to its reactivity to air and many other oxygen containing substances, phospho-rus is not found free in nature but it is widely distributed in many different minerals. Phosphate rock, which is partially made of apatite (an impure tri-calcium phosphate mineral) is an important commercial source of this element. Large deposits of apatite are in Russia, Morocco, Florida, Idaho, Tennessee, Utah, and elsewhere.The white allotrope can be produced using several different methods. In one process,

tri-calcium phosphate, which is derived from phosphate rock, is heated in an electric or fuel-fired furnace in the presence of carbon and silica. Elemental phosphorus is then liberated as a vapor and can be collected under phosphoric acid.


Sulfur

Sulfur (or sulphur, see spelling) is the chemical element in the periodic table that has the symbol S, atomic number 16 and atomic weight of 32.065. It is a Chalcogen a Non-metallic element.

• Name: Sulfur• Symbol: S• Atomic number: 16• Atomic weight: 32.065• Standard state: solid at 298 K• CAS Registry ID: 7704-34-9• Group in periodic table: 16• Group name: Chalcogen• Period in periodic table: 3• Block in periodic table: p-block• Colour: lemon yellow• Classification: Non-metallic

An abundant tasteless odorless multivalent non-metal, sulfur is best known as yellow crystals and occurs in many sulfide and sulfate minerals and even in its native form (especially in volcanic regions). It is an essential element in all living organisms and is needed in several amino acids and hence in many proteins. It is primarily used in fertilizers but is also widely used in gunpowder, laxatives, matches, insecticides and fungicides.


This non-metal is pale yellow in appearance, soft, light, with a distinct odor when allied with hydrogen (rotten egg smell, it should be noted that, contrary to popular belief, the element itself does not have such an odor). It burns with a blue flame that emits a peculiar suffocating odor (sulfur dioxide, SO2). Sulfur is insoluble in water but soluble in carbon disulfide. Common oxidation states of sulfur include -2, +2, +4 and +6. In all states, solid, liquid, and gaseous, sulfur has allotropic forms, whose relation-ships are not completely understood. Crystalline sulfur can be shown to form an 8 membered sulfur ring, S8.Sulfur can be obtained in two crystalline modifications, in orthorhombic octahedra,

or in monoclinic prisms, the former of which is the more stable at ordinary tempera-tures.


Previous Page

Applications

It is used for many industrial processes such as the production of sulfuric acid (H2SO4) for batteries and detergents, the production of gunpowder, and the vulcani-zation of rubber. Sulfur is used as a fungicide, and in the manufacture of phosphate fertilizers. Sulfites are used to bleach papers and dried fruits. Sulfur also finds use in matches and fireworks. Sodium or ammonium thiosulfate are used as photographic fixing agents. Epsom salts, magnesium sulfate, can be used as a laxative, as a bath ad-ditive, as an exfoliant, or a magnesium supplement in plant nutrition.

Biological role

The amino acids cysteine, methionine, homocysteine, and taurine contain sulfur, as do some common enzymes, making sulfur a necessary component of all living cells. Disulfide bonds between polypeptides are very important in protein assembly and structure. Some forms of bacteria use hydrogen sulfide (H2S) in the place of water as the electron donor in a primitive photosynthesis-like process. Sulfur is absorbed by plants from soil as sulfate ion. Inorganic sulfur forms a part of iron-sulfur clusters, and sulfur is the bridging ligand in the CuA site of cytochrome c oxidase.The massive burning of coal by industry and power plants liberates huge amounts of

sulfur dioxide, which reacts with atmospheric water and oxygen to produce sulfuric acid. By changing the pH of soil and freshwater bodies, the resulting acid rain has led to substantial damage to the natural environment in some regions.

History

Sulfur (Sanskrit, sulvere; Latin sulpur) was known in ancient times, and is referred to in the Biblical story of Pentateuch (Genesis). English translations of this common-ly refer to sulfur as "brimstone", giving rise to the name of 'Fire and brimstone' ser-mons, which are sermons where hell and eternal damnation for sinners is stressed. It is from this part of the bible that hell is thought to smell of sulfur. Homer mentioned "pest-averting sulfur" in the 9th century BC and in 424 BC, the tribe of Bootier de-stroyed the walls of a city by burning a mixture of coal, sulfur, and tar under them. Sometime in the 12th century, the Chinese invented gun powder which is a mixture of potassium nitrate (KNO3), carbon, and sulfur.Early alchemists gave sulfur its own alchemical symbol which was a triangle at the

top of a cross. Through experimentation, alchemists knew that the element mercury can be combined with sulfur. In the late 1770s, Antoine Lavoisier helped convince the scientific community that sulfur was an element and not a compound.

Occurrence

Sulfur occurs naturally in large quantities compounded to other elements in sulfides (example: pyrite) and sulfates (example: gypsum). It is found in its free form near hot springs and volcanic regions (hence the name brimstone, from being found at the brim of craters) and in ores like cinnabar, galena, sphalerite and stibnite. This element is also found in small amounts in coal and petroleum, which produce sulfur dioxide

when burned. Fuel standards increasingly require sulfur to be extracted from fossil fuels because sulfur dioxide combines with water droplets to produce acid rain. This extracted sulfur is then refined and represents a large portion of sulfur production. It is also mined along the US Gulf coast by the Frasch process, which involves pumping a mixture of compressed air and superheated water into sulfur containing deposits (such as salt domes). The hot water melts the sulfur, and the pressure of the air drives the molten sulfur to the surface.Through its major derivative, sulfuric acid, sulfur ranks as one of the more-important

elements used as an industrial raw material. It is of prime importance to every sector of the world's industrial and fertilizer complexes. Sulfuric acid production is the ma-jor end use for sulfur, and consumption of sulfuric acid has been regarded as one of the best indexes of a nation's industrial development. More sulfuric acid is produced in the United States every year than any other chemical.The distinctive colors of Jupiter's volcanic moon Io, are from various forms of molten,

solid and gaseous sulfur. There is also a dark area near the Lunar crater Aristarchus that may be a sulfur deposit. Sulfur is also present in many types of meteorites.

CompoundsMany of the unpleasant odors of organic matter are based on sulfur-containing com-

pounds such as hydrogen sulfide, which has the characteristic smell of rotten eggs. Dissolved in water, hydrogen sulfide is acidic

(pKa1 = 7.00, pKa2 = 12.92) and will react with metals to form a series of metal sulfides. Natural metal sulfides are found, especially those of iron. Iron sulfides are called iron pyrite, the so called fool's gold. Interestingly, pyrite can show semiconductor prop-erties. Galena, a naturally occurring lead sulfide, was the first semiconductor discov-ered, and found a use as a signal rectifier in the early “cat's whisker” crystal radios).

Polymeric sulfur nitride has metallic properties even though it doesn't contain any metal atoms. This compound also has unusual electrical and optical properties. Amor-phous or "plastic" sulfur can be produced through the rapid cooling of molten sulfur. X-ray crystallography studies show that the amorphous form may have a helical struc-ture with eight atoms per turn. This form is metastable at room temperature, howev-er, and gradually reverts back to crystalline form.

Other important compounds of sulfur include: * Sodium dithionite, Na2S2O4, a powerful reducing agent. * Sulfurous acid, H2SO3, created by dissolving SO2 in water. Sulfurous acid and the

corresponding sulfites are fairly strong reducing agents. Other compounds derived from SO2 include the pyrosulfite ion (S2O52-). * The thiosulfates (S2O32-). Thiosul-fates are used in photographic fixing, are oxidizing agents, and ammonium thiosul-fate is being investigated as a cyanide replacement in leaching gold. * Compounds of dithionic acid (H2S2O6) * The polythionic acids, (H2SnO6), where n can range from 3 to 80. * The sulfates, the salts of sulfuric acid. Epsom salts are magnesium sulfate. * Sulfides are simple ccompunds of sulfur with some other chemical element. * Sulfuric acid reacting with SO3 in equimolar ratios forms pyrosulfuric acid.


Previous Page

* Peroxymonosulfuric acid and peroxydisulfuric acids, made from the action of SO3 on concentrated H2O2, and H2SO4 on concentrated H2O2 respectively. * Tetrasulfur tetranitride S4N4. * Thiocyanates are compounds containing the thiocyanate ion, SCN- * Thiocyanogen, (SCN)2. * A thioether is a molecule with the form R-S-R', where R and R' are organic groups.

These are the sulfur equivalents of ethers. * A thiol (also known as a mercaptan) is a molecule with an -SH functional group.

These are the sulfur equivalents of alcohols. * A thiolate ion has an -S- functional group attached. These are the sulfur equivalent

of alkoxide ions.

IsotopesSulfur has 18 isotopes, of which four stable isotopes: S-32 (95.02%), S-33 (0.75%), S-34

(4.21%), and S-36 (0.02%). Other than 35S, the radioactive isotopes of sulfur are all short lived. Sulfur-35 is formed from cosmic ray spallation of argon- 40 in the atmosphere. it has a half-life of 87 days.When sulfide minerals are precipitated, isotopic equilibration among solids and liq-

uid may cause small differences in the dS-34 values of co-genetic minerals. The differ-ences between minerals can be used to estimate the temperature of equilibration. The dC-13 and dS-34 of co-existing carbonates and sulfides can be used to determine the pH and oxygen fugacity of the ore-bearing fluid during ore formation.In most forest ecosystems, sulfate is derived mostly from the atmosphere; weathering

of ore minerals and evaporites also contributes some sulfur. Sulfur with a distinctive isotopic composition has been used to identify pollution sources, and enriched sulfur has been added as a tracer in hydologic studies. Differences in the natural abundanc-es can also be used in systems where there is sufficient variation in the S-34 of eco-system components. Rocky Mountain lakes thought to be dominated by atmospheric sources of sulfate have been found to have different dS-34 values from lakes believed to be dominated by watershed sources of sulfate.


Chlorine

Chlorine (from Gr. Chloros, meaning "pale green"), is the chemical element with sym-bol Cl, atomic number 17 and atomic weight of 35.453 . It is a Non-metallic Halogen.

• Name: Chlorine• Symbol: Cl• Atomic number: 17• Atomic weight: 35.453• Standard state: gas at 298 K• CAS Registry ID: 7782-50-5• Group in periodic table: 17• Group name: Halogen• Period in periodic table: 3• Block in periodic table: p-block• Colour: yellowish green• Classification: Non-metallic

Chlorine gas is greenish yellow, is two and one half times as heavy as air, has an in-tensely disagreeable suffocating odor, and is exceedingly poisonous. It is a powerful oxidizing, bleaching, and disinfecting agent. As part of common salt and other com-pounds, it is abundant in nature and necessary to most forms of life, including the human body.


The pure chemical element has the physical form of a diatomic green gas. The name chlorine is derived from chloros, meaning green, referring to the color of the gas. This element is a member of the salt-forming halogen series and is extracted from chlorides through oxidation and more commonly, by electrolysis. Chlorine is a green-ish-yellow gas that combines readily with nearly all other elements. At 10°C one liter of water dissolves 3.10 liters of chlorine and at 30°C only 1.77 liters.

Applications

Chlorine is an important chemical in water purification, in disinfectants in bleach and in mustard gas. Chlorine is also used widely in the manufacture of many everyday items. * Used to kill bacteria and other microbes from drinking water supplies and swim-


Previous Page

ming pools. Even small water supplies are now routinely chlorinated. * Used widely in paper product production, antiseptic, dyestuffs, food, insecticides,

paints, petroleum products, plastics, medicines, textiles, solvents, and many other consumer products. Organic chemistry uses this element extensively as an oxidizing agent and in substitution because chlorine often imparts many desired properties in an organic compound when it is substituted for hydrogen (synthetic rubber). Others uses are in the production of chlorates, chloroform, carbon tetrachloride, and in the bromine extraction..

History

Chlorine (greenish yellow) was discovered in 1774 by Carl Wilhelm Scheele, who mis-takenly thought it contained oxygen. Chlorine was given its name in 1810 by Humphry Davy, who insisted that it was in fact an element.

Occurrence

In nature chlorine is found only as the chloride ion. Chlorides make up much of the salt dissolved in the Earth's oceans - about 1.9% of the mass of seawater is chloride ions. Even higher concentrations of chloride are dissolved in the Dead Sea and in un-derground brine deposits. Most chlorides are soluble in water, so solid chlorides are usually only found in abundance in dry climates, or deep underground. Common chlo-ride minerals include halite (sodium chloride), sylvite (potassium chloride), and car-nallite (potassium magnesium chloride hexahydrate). Industrially, elemental chlorine is usually produced by the electrolysis of sodium chloride dissolved in water. Along with chlorine, this chloralkali process yields hydrogen gas and sodium hydroxide,

Compounds

Compounds of chlorine include chlorides, chlorites, chlorates, perchlorates, chlora-mines.

Isotopes

There are two principal stable isotopes of chlorine, of mass 35 and 37, found in the relative proportions of 3:1 respectively, giving chlorine atoms in bulk an apparent atomic weight of 35.5. Chlorine has 9 isotopes with mass numbers ranging from 32 to 40. Only three of these isotopes occur naturally: stable Cl-35 (75.77%) and Cl-37 (24.23%), and radioactive Cl-36. The ratio of Cl-36 to stable Cl in the environment is about 700 E -151. Cl-36 is produced in the atmosphere by spallation of Ar-36 by inter-actions with cosmic ray protons. In the subsurface environment, Cl-36 is generated primarily as a result of neutron capture by Cl-35 or muon capture by Ca-40. Cl-36 decays to S-36 and to Ar-36, with a combined half-life of 308,000 years. The half-life of this hydrophilic nonreactive isotope makes it suitable for geologic dating in the range of 60,000 to 1 million years. Additionally, large amounts of Cl-36 were produced by irradiation of seawater during atmospheric detonations of nuclear weapons between 1952 and 1958. The residence time of Cl-36 in the atmosphere is about 1 week. Thus, as an event marker of 1950s water in soil and ground water, Cl-36 is also useful for dating

waters less than 50 years before the present. Cl-36 has seen use in other areas of the geological sciences, including dating ice and sediments.



Previous Page

Argon

Argon is the chemical element in the periodic table that has the symbol Ar, atomic number 18 and atomic weight of 39.948. It is a Nobel Gas.

• Name: Argon• Symbol: Ar• Atomic number: 18• Atomic weight: 39.948• Standard state: gas at 298 K• CAS Registry ID: 7440-37-1• Group in periodic table: 18• Group name: Noble gas• Period in periodic table: 3• Block in periodic table: p-block• Colour: colourless• Classification: Non-metallic

The third noble gas, in group 18, argon makes up about 1% of the Earth's atmosphere.


Argon is 2.5 times as soluble in water as nitrogen which is approximately the same solubility as oxygen. This chemically inert element is colorless and odorless in both its liquid and gaseous forms. There are no known true chemical compounds that contain argon. The creation of argon hydroflouride (HArF) was reported by researchers at the University of Helsinki in 2000. A highly unstable compound with fluorine has been reported but not yet proven. Although no chemical compounds of argon are present-ly confirmed, argon can form clathrates with water when atoms of it are trapped in a lattice of the water molecules.

Applications

It is used in lighting since it will not react with the filament in a lightbulb even under high temperatures and other cases where diatomic nitrogen is an unsuitable (semi-)inert gas.

Other uses:

Used as an inert gas shield in many forms of welding, including mig and tig (where the "I" stands for inert). As a non-reactive blanket in the manufacture of titanium and other reactive elements. As a protective atmosphere for growing silicon and germani-um crystals. Argon-39 has been used for a number of applications, primarily ice cor-ing. It has also been used for ground water dating. Cryosurgery procedures such as cryoablation uses liquefied argon to destroy cancer cells. Argon is also used in techni-cal SCUBA diving to inflate the dry suit, due to its nonreactive, heat isolating effect.

History

Argon (Greek argos meaning "inactive") was suspected to be present in air by Henry Cavendish in 1785 but was not discovered until 1894 by Lord Rayleigh and Sir William Ramsay.

Occurrence

This gas is isolated through liquid air fractionation since the atmosphere contains only 0.94% volume of argon (1.29% mass). The Martian atmosphere in contrast contains 1.6% of Ar-40 and 5 ppm Ar-36.

Isotopes

The main isotopes of argon found on Earth are Ar-40, Ar-36, and Ar-38. Naturally oc-curring K-40 with a half-life of 1.250 x 109 years, decays to stable Ar-40 (11.2%) by elec-tron capture and by positron emission, and also decays to stable Ca-40 (88.8%) by neg-atron emission. These properties and ratios are used to determine the age of rocks.In the Earth's atmosphere, Ar-39 is made by cosmic ray activity, primarily with Ar-40.

In the subsurface environment, it is also produced through neutron-capture by K-39 or alpha emission by calcium. Argon-37 is created from the decay of calcium-40 as re-sult of subsurface nuclear explosions. It has a half-life of 35 days.



Previous Page

Potassium

Potassium is a chemical element in the periodic table that has the symbol K, (L. Kali-um) atomic number 19 and Atomic weigh of: 39.0983. It is a Alkali metal.

• Name: Potassium• Symbol: K• Atomic number: 19• Atomic weight: 39.0983• Standard state: solid at 298 K• CAS Registry ID: 7440-09-7• Group in periodic table: 1• Group name: Alkali metal• Period in periodic table: 4• Block in periodic table: s-block• Colour: silvery white• Classification: Metallic

This is a soft, silvery-white metallic alkali metal that occurs naturally bound to oth-er elements in seawater and many minerals. It oxidizes rapidly in air, is very reactive, especially in water, and resembles sodium chemically.


Potassium is the second lightest metal. It is a soft solid that easily is cut with a knife and is silvery in color on fresh surfaces. It oxidizes in air rapidly and must be stored in mineral oil for preservation. Similar to other alkali metals, potassium reacts violently with water producing hydrogen. When in water it may catch fire spontaneously. Its salts emit a violet color when exposed to a flame.

Applications

* Potassium oxide, best known as potash, is primarily used in fertilizer. * Potassium nitrate is used in gunpowder. * Potassium carbonate is used in glass manufacture. * NaK an alloy of sodium and potassium is used as a heat-transfer medium.* This element is an essential component needed in plant growth and is found in

most soil types.

* In animal cells potassium ions are vital to keeping cells alive (see Na-K pump) * Potassium chloride is used as a substitute for table salt and is also used to stop the

heart, e.g. in cardiac surgery and in executions by lethal injection.Many potassium salts are very important, and include, potassium; bromide, carbon-

ate, chlorate, chloride, chromate, cyanide, dichromate, hydroxide, iodide, nitrate, sulfate.

History

Potassium ( English, potash L. kalium ) was discovered in 1807 by Sir Humphry Davy who derived it from caustic potash (KOH). This alkali metal was the first metal that was isolated by electrolysis.

Occurrence

This element makes up about 2.4% of the weight of the Earth's crust and is the sev-enth most abundant element in it. Due to its insolubility, it is very difficult to obtain potassium from its minerals.However, other minerals, such as carnallite, langbeinite, polyhalite, and sylvite are

found in ancient lake and sea beds. These minerals form extensive deposits in these environments, making extracting potassium and its salts more economical. The prin-ciple source of potassium, potash is mined in California, Germany, New Mexico, Utah, and in other places around the world. At 3000 ft below the surface of Saskatchewan are large deposits of potash which may become important sources of this element and its salts in the future.The oceans are another source of potassium but the quantity present in a given vol-

ume of seawater is relatively low compared to sodium.Potassium can be isolated through electrolysis of its hydroxide in a process that has

changed little since Davy. Thermal methods also are employed in potassium produc-tion. Potassium is almost never found unbound in nature. However, in living organ-isms K+ ions are important in the physiology of excitable cells.

Isotopes

There are seventeen isotopes of potassium known to exist. The non-synthetic form of potassium are composed of three isotopes: K-39 (93.3%), K-40 (0.01%) and K-41 (6.7%). Naturally occurring K-40 decays to stable Ar-40 (11.2%) by electron capture and by positron emission, and decays to stable Ca-40 (88.8%) by negatron emission; K-40 has a half-life of 1.250 * 109 years.The decay of K-40 to Ar-40 is commonly used as a method for dating rocks. The con-

ventional K-Ar dating method depends on the assumption that the rocks contained no argon at the time of formation and that all the subsequent radiogenic argon (i.e., Ar-40) was quantitatively retained, i.e., closed system. Minerals are dated by measure-ment of the concentration of potassium, and the amount of radiogenic Ar-40 that has accumulated. The minerals that are best suited for dating include biotite, muscovite, and plutonic/high grade metamorphic hornblende, and volcanic feldspar; whole rock samples from volcanic flows and shallow instrusives can also be dated if they are un-altered.


Previous Page

Outside of dating, K isotopes have been used extensively in studies of weathering; K isotopes have also be used for nutrient cycling studies because K is a macro-nutrient required for life. K-40 occurs in natural potassium (and thus in some commercial salt substitutes) in sufficient quantity that large bags of those substitutes can be used as a radioactive source for classroom demonstrations.

Potassium in the body

Potassium in the body exists as a monovalent positive ion (a cation), K+, concentrated by energy-requiring mechanisms primarily within cells (intracellular), where it com-prises the cell's most abundant monovalent inorganic cation. The body regulates the K+ concentration in blood moderately closely, as substantial fluctuations can affect action potentials, causing heart and nervous problems. Many antibiotics, such as the one produced by the bacterium Bacillus brevis, affect cells by setting up positive ion gates, where the K+ and Na+ ions are permitted to cross the membrane, thus disrupt-ing the action potential of the cell membrane.The body maintains potassium ion concentration relatively low in blood plasma (usu-

ally 3.5 - 5.0 mmol/L), but much higher inside cells (about 100 mmol/L). Abnormally low blood levels, hypokalemia, and abnormally high levels, hyperkalemia, both can adversely affect the heart.


Calcium

Calcium is a chemical element in the periodic table that has the symbol Ca, atomic number 20 and atomic weight of 40.078. It is a Alkaline Earth Metal.

• Name: Calcium• Symbol: Ca• Atomic number: 20• Atomic weight: 40.078• Standard state: solid at 298 K• CAS Registry ID: 7440-70-2• Group in periodic table: 2• Group name: Alkaline earth metal• Period in periodic table: 4• Block in periodic table: s-block• Colour: silvery white• Classification: Metallic

Calcium is a soft grey alkaline earth metal that is used as a reducing agent in the ex-traction of thorium, zirconium and uranium. This element is also the fifth most abun-dant element in the earth's crust. It is essential for living organisms, particularly in cell physiology.


Calcium is a rather hard element that is purified by electrolysis from calcium fluoride that burns with a yellow-red flame and forms a white nitride coating when exposed to air. It reacts with water displacing hydrogen and forming calcium hydroxide.

Applications

Calcium is an important component of a healthy diet. Its minor deficit can affect bone and teeth formation. Its excess can lead to kidney stones. Vitamin D is needed to absorb calcium. Dairy products are an excellent source of calcium. For more informa-tion about Ca in living nature, see calcium in biology.

Other uses include: * Reducing agent in the extraction of other metals such as Uranium, Zirconium, and


Previous Page

Thorium. * Deoxidizer, desulfurizer, or decarburizer for various ferrous and nonferrous alloys. * Alloying agent used in the production of aluminium, beryllium, copper, lead, and

magnesium alloys.

History

(Latin calx, Lime) Lime was prepared and used by the Romans as early as the 1st cen-tury, but calcium was not discovered until 1808. After learning that Berzelius and Pon-tin prepared calcium amalgam by electrolyzing lime in mercury, Sir Humphry Davy was able to isolate the impure metal.

Occurrence

Calcium is the fifth most abundant element in the earth's crust (forming more than 3%) and is an essential part of leaves, bones, teeth, and shells. Due to its chemical reac-tivity with air and water, calcium is never found in nature unbound to other elements, except in living organisms where Ca2+ plays a key role in cell physiology. This metallic element is found in quantity in limestone, gypsum, and fluorite. Apatite is the fluo-rophosphate or chlorophosphate of calcium. Electrolysis of molten calcium chloride (CaCl2) can be used to isolate pure calcium.

Compounds

Quicklime (CaO) is used in many chemical refinery processes and is made by heating and carefully adding water to limestone. When CaO is mixed with sand it hardens into a mortar and is turned into plaster by carbon dioxide uptake. Mixed with other com-pounds, CaO forms an important part of Portland cement.When water percolates through limestone or other soluble carbonate rocks, it par-

tially disolves part of the rock and causes cave formation and characteristic stalactites and stalagmites and also forms hard water. Other important calcium compounds are nitrate, sulfide, chloride, carbide, cyanamide, and hypochlorite.

Isotopes

Calcium has six stable isotopes, two of which occur in nature: stable Ca-40 and radio-active Ca-41 with a half-life = 103,000 years. 97% of the element is in the form of Ca-40. Ca-40 is one of the daughter products of K-40 decay, along with Ar-40. While K-Ar dating has been used extensively in the geological sciences, the prevalence of Ca-40 in nature has impeded its use in dating. Techniques using mass spectrometry and a dou-ble spike isotope dilution have been used for K-Ca age dating. Unlike cosmogenic iso-topes that are produced in the atmosphere, Ca-41 is produced by neutron activation of Ca-40. Most of its production is in the upper metre or so of the soil column where the cosmogenic neutron flux is still sufficiently strong. Ca-41 has received much atten-tion in stellar studies because Ca-41 decays to K-41, a critical indicator of solar-system anomalies.



Previous Page

Scandium

Scandium is a chemical element in the periodic table that has the symbol Sc, atomic number 21 and Atomic weight: 44.955912. It is a Transition Metal.

• Name: Scandium• Symbol: Sc• Atomic number: 21• Atomic weight: 44.955912• Standard state: solid at 298 K• CAS Registry ID: 7440-20-2• Group in periodic table: 3• Group name: (none)• Period in periodic table: 4• Block in periodic table: d-block• Colour: silvery white• Classification: Metallic

A soft, silvery, white transition element, scandium occurs in rare minerals from Scan-dinavia and it is sometimes classified along with yttrium and the lanthanides as a rare earth.


Scandium is a rare, soft, silvery, trivalent, very light metallic element that develops a slightly yellowish or pinkish cast when exposed to air. This element resembles yttrium and rare earth metals more than it resembles aluminium or titanium (which are clos-er on the periodic table). The most common oxidation state of scandium is +3 and this metal is not attacked by a 1:1 mixture of HNO3 and 48% HF.

Applications

Approximately 20 kg of scandium (as Sc2O3) are used annually in the United States to make high-intensity lights. The radioactive isotope Sc-46 is used in oil refinery crack-ers as a tracing agent. When scandium iodide is added to mercury vapor lamps a high-ly efficient artificial sunlight-like light source is produced which is used in indoor or night-time color televisions.Approximately 80 kg of scandium is used in lightbulbs globally per year. The main

usage by volume is in aluminium-scandium alloys for sporting goods (bikes, baseball bats, etc.) When added to aluminium, it can produce improvements in strength, duc-tility, aging response and grain refinement through the formation of the Al3Sc phase. Furthermore, it has been shown to reduce solidification cracking during the welding of high strength Al alloys. Sc is thus finding applications in the aerospace and sports equipment industries which rely of high performance Al alloys.

History

Scandium (Latin Scandia meaning "Scandinavia") was discovered by Lars Fredrick Nilson in 1879 while he and his team were looking for rare earth metals. Nilson used spectrum analysis to find the new element within the minerals euxenite and gadolin-ite. To isolate the element he processed 10 kilograms of euxenite with other rare-earth residues to obtain about 2 grams of very pure scandium oxide (Sc2O3).Dmitri Mendeleev, in 1869, predicted the existence and some properties of this ele-

ment, which he called ekaboron, using his periodic law. Per Teodor Cleve discovered scandium oxide at about the same time as Nilson but unlike Nilson, Cleve determined that scandium was identical to ekaboron.In 1937 metallic scandium was prepared for the first time by electrolysis of a eutectic

melt of potassium, lithium, and scandium chlorides at 700 to 800°C. Tungsten wire in a pool of liquid zinc were the electrodes in a graphite crucible. The first pound of 99% pure scandium metal wasn't produced until 1960.

Occurrence

Rare minerals from Scandinavia and Malagasy such as thortveitite, euxenite and gad-olinite are the only known concentrated sources of this element (which is never found as a free metal).Element 21 is the 23rd most abundant element in the sun and similar stars but on

earth it is only the 50th most abundant element. Scandium is distributed widely on earth, occurring in trace quantities in over 800 minerals. The blue color of the aqua-marine variety of beryl is thought to be caused by scandium. It is an important part of the rare mineral thortveitite and is found in residues that remain after tungsten is extracted from Zinnwald wolframite.Thortveitite is the primary source of scandium with uranium mill tailings by-prod-

ucts also being an important source. Pure scandium is commercially produced by reducing scandium fluoride with calcium metal.The main source source of scandium is from military stockpiles from the former Sovi-

et Union, which were themselves extracted from uranium tailings. There is no primary production in the Americas or Europe.

Isotopes

Naturally occurring scandium is composed of 1 stable isotope Sc-45. 13 radioisotopes have been characterized with the most stable being Sc-46 with a half-life of 83.79 days, Sc-47 with a half-life of 3.3492 days, and Sc-48 with a half-life of 43.67 hours. All of the remaining radioactive isotopes have half-lifes that are less than 4 hours and the ma-jority of these have half lifes that are less than 2 minutes. This element also has 5 meta


Previous Page

states with the most stable being Scm-44.The isotopes of scandium range in atomic weight from 39.978 amu (Sc-40) to 53.963

amu (Sc-54). The primary decay mode before the only stable isotope, Sc-45, is electron capture and the primary mode after is beta emission. The primary decay products before Sc-45 are element 20 (calcium) isotopes and the primary products after are ele-ment 22 (titanium) isotopes.


Titanium

Titanium is a chemical element in the periodic table that has the symbol Ti, atomic number 22 and atomic weight of 47.867. It is a Transition metal.

• Name: Titanium• Symbol: Ti• Atomic number: 22• Atomic weight: 47.867• Standard state: solid at 298 K• CAS Registry ID: 7440-32-6• Group in periodic table: 4• Group name: (none)• Period in periodic table: 4• Block in periodic table: d-block• Colour: silvery metallic• Classification: Metallic

A light, strong, white-metallic, lustrous, corrosion-resistant transition metal, titani-um is used in strong light-weight alloys and in white pigments. This element occurs in numerous minerals with the main sources being rutile and ilmenite.


Titanium is a metallic element which is well known for its excellent corrosion resis-tance (almost as resistant as platinum) and for its high strength-to-weight ratio. It is a light, strong, easily fabricated metal with low density (40% as dense as steel) that, when pure, is quite ductile, easy to work, lustrous, and metallic-white in color. The relatively high melting point of this element makes it useful as a refractory metal. Titanium is as strong as steel, but 45% lighter; it is 60% heavier than aluminium, but twice as strong. These properties make titanium very resistant to the usual kinds of metal fatigue.This metal forms a passive oxide coating when exposed to air but when it is in an ox-

ygen-free environment it is ductile. The metal, which burns when heated in air, is also the only element that can burn in pure nitrogen gas. Titanium is resistant to dilute sulfuric and hydrochloric acid, along with chlorine gas, chloride solutions, and most organic acids.Experiments have shown that natural titanium becomes very radioactive after it is

bombarded with deuterons, emitting mainly positrons and hard gamma rays. The


Previous Page

metal is dimorphic with the hexagonal alpha form changing into the cubic beta form very slowly at around 880Â°C. When it is red hot the metal combines with oxygen, and when it reaches 550°C it combines with chlorine.

Applications

Approximately 95% of titanium is consumed in the form of titanium dioxide (TiO2), an intensely white permanent pigment with good covering power in paints, paper, and plastics. Paints made with titanium dioxide are excellent reflectors of infrared radia-tion and are therefore used extensively by astronomers.Because of its strength, light weight, extraordinary corrosion resistance, and ability

to withstand extreme temperatures, titanium alloys are principally used in aircraft and missiles, although applications in consumer products such as golf clubs, bicycles, wedding bands, and laptop computers are becoming more common. Titanium is often alloyed with aluminium, vanadium, iron, manganese, molybdenum and with other metals.

Other Uses: * Due to excellent resistance to sea water, it is used to make propeller shafts and

rigging. * It is used to produce relatively soft artificial gemstones. * Titanium tetrachloride (TiCl4), a colorless liquid, is used to iridize glass and be-

cause it fumes strongly in moist air it is also used to make smoke screens. * In addition to being a very important pigment, titanium dioxide is also used in

sunscreens due to its ability to protect skin by itself. * Because it is considered to be physiologically inert, the metal is used in joint re-

placement implants such as hip ball and sockets. * Its inertness and ability to be attractively colored makes it a popular metal for use

in body piercing. * Titanium has the unusual ability to osseointegrate, enabling use in dental im-

plants.

A potential use of titanium is in desalination plants. Titanium has occasionally been used in construction: the 150-foot memorial to Yuri Gagarin, the first man to travel in space, in Moscow, is made of titanium for the metal's attractive color and association with rocketry. The Guggenheim Museum Bilbao and the Cerritos Library were the first buildings, respectively, in Europe and North America to be sheathed in titanium pan-els.

History

Titanium (Latin Titans, the first sons of Gaia) was discovered in England by Reverend William Gregor in 1791 who recognized the presence of a new element in ilmenite. The element was rediscovered several years later by German chemist Martin Heinrich Kl-aproth in rutile ore. In 1795 Klaproth named the new element after the Titans of Greek mythology.Pure metallic titanium (99.9%) was first prepared in 1910 by Matthew A. Hunter by

heating TiCl4 with sodium in a steel bomb at 700-800°C.

Titanium metal was not used outside the laboratory until 1946 when William Justin Kroll proved that titanium could be commercially produced by reducing titanium tet-rachloride with magnesium (which is the method still used today).

Occurrence

Titanium metal is not found unbound to other elements in nature but the element is the ninth most abundant element in the Earth's crust (0.6% by mass) and is present in most igneous rocks and in sediments derived from them. It occurs primarily in the minerals anatase, brookite, ilmenite, leucoxene, perovskite, rutile, and sphene and is found in titanates and in many iron ores. Of these minerals, only ilmenite, leucoxene, and rutile have significant economic importance. Because it reacts easily with oxygen and carbon at high temperatures it is difficult to prepare pure titanium metal. Signifi-cant titanium ore deposits are in Australia, Scandinavia, North America and Malaysia.This metal is found in meteorites and has been detected in the sun and in M-type

stars. Rocks brought back from the moon during the Apollo 17 mission are composed of 12.1% TiO2. Titanium is also found in coal ash, plants, and even the human body.

Production

Titanium metal is produced commercially by reducing TiCl4 with magnesium, a pro-cess developed in 1946 by William Justin Kroll. This is a complex, and expensive batch process, but a newer process called the "FFC-Cambridge" method may displace this older process. This method uses the feedstock titanium dioxide powder (which is a re-fined form of rutile) to make the end product which is a continuous stream of molten titanium suitable for immediate use in the manufacture of commercial alloys.It is hoped that the FFC-Cambridge method will render titanium a less rare and ex-

pensive material for the aerospace industry and the luxury goods market, and will be seen in many products currently manufactured using aluminium and specialist grades of steel.

Compounds

Although titanium metal is relatively uncommon, due to the cost of extraction, ti-tanium dioxide is cheap, readily available in bulk, and very widely used as a white pigment in paint, plastic and construction cement. TiO2 powder is chemically inert, resists fading in sunlight, and is very opaque: this allows it to impart a pure and bril-liant white color to the brown or gray chemicals that form the majority of household plastics.Pure titanium dioxide has a very high index of refraction and an optical dispersion

higher than diamond. Star sapphires and rubies get their asterism from the titanium dioxide present in them.


Previous Page

From Wikipedia, the free encyclopedia and webelements Vanadium

Vanadium is a chemical element in the periodic table that has the symbol V, atomic number 23 and atomic weight of 50.9415. It is a Transition Metal.

• Name: Vanadium• Symbol: V• Atomic number: 23• Atomic weight: 50.9415• Standard state: solid at 298 K• CAS Registry ID: 7440-62-2• Group in periodic table: 5• Group name: (none)• Period in periodic table: 4• Block in periodic table: d-block• Colour: silvery grey metallic• Classification: Metallic

A rare, soft and ductile element, vanadium is found combined in certain minerals and is used mainly to produce certain alloys.


Vanadium is a soft and ductile, bright white metal. It has good resistance to corrosion by alkalis, sulphuric and hydrochloric acid. It oxidizes readily at about 933 K. Vana-dium has good structural strength and a low fission neutron cross section, making it useful in nuclear applications. It is intermediate between the metals and the non-met-als, having both basic and acid properties.Common oxidation states of vanadium include +2, +3, +4 and +5. A popular experiment

with ammonium vanadate (NH4VO3), reducing the compound with zinc metal, can demonstrate colorimetrically all four of these vanadium oxidation states. A +1 oxida-tion state is also rarely seen.

Applications

Approximately 80% of vanadium produced is used as ferrovanadium or as a steel ad-ditive.


Previous Page

Other Uses: * In such alloys as: * Specialty stainless steel, e.g. for use in surgical instruments and tools. * Rust resistant and high speed tool steels. * Mixed with aluminium in titanium alloys used in jet engines and high-speed air-

frames * Vanadium steel alloys are used in axles, crankshafts, gears, and other critical com-

ponents. * It is an important carbide stabilizer in making steels. * Because of its low fission neutron cross section, vanadium has nuclear applica-

tions. * Vanadium foil is used in cladding titanium to steel. * Vanadium-gallium tape is in superconducting magnets (175,000 gauss). * Vanadium compounds are used as catalysts in producing maleic anhydride and sul-

furic acid. * Vanadium pentoxide (V2O5) is used in ceramics and as a catalyst. * Glass coated with vanadium dioxide (VO2) can block infrared radiation (and not

visible light) at some specific temperature.

History

Vanadium (Scandinavian goddess, Vanadis) was originally discovered by Andres Man-uel del Rio (a Spanish mineralogist) at Mexico City in 1801, who called it "brown lead" (now named vanadinite).Through experimentation, he saw that the colors it exhibited were reminiscent of

chromium, so he named the element panchromium. He later renamed this compound erythronium, since most of the salts turned red when heated. A French chemist in-correctly declared that del Rio's new element was only impure chromium. Del Rio thought himself to be mistaken and accepted the statement of the French chemist.In 1831, Sefström of Sweden rediscovered vanadium in a new oxide he found while

working with some iron ores and later that same year Friedrich WÃ¶hler confirmed del Rio's earlier work.Metallic vanadium was isolated by Henry Enfield Roscoe in 1867, who reduced the

vanadium chloride (VCl3) with hydrogen. The name vanadium comes from Vanadis, the goddess of beauty in Scandinavian mythology because the element has beautiful multicolored chemical compounds.

Biological Role

In biology, a vanadium atom is an essential component of some enzymes, particularly the vanadium nitrogenase used by some nitrogen-fixing microorganisms. Vanadium is essential for electron transfer chain of ascidians, or sea squirts. The concentration of vanadium in their bodies is one million times higher than the concentration of va-nadium in the water around them. Rats and chickens are also known to require vana-dium in very small amounts and deficiencies result in reduced growth and impaired reproduction.Administration of oxovanadium compounds has been shown to alleviate diabetes

mellitus symptoms in certain animal models and humans. Much like the chromium

effect on sugar metabolism, the mechanism of this effect is unknown.

OccurrenceVanadium is never found unbound in nature but it does occur in about 65 different

minerals among which are patronite (VS4), vanadinite [Pb5(VO4)3Cl], and carnotite [K2(UO2)2(VO4)2.3H2O].Vanadium is also present in bauxite, and in carbon containing deposits such as crude

oil, coal, oil shale and tar sands. The spectra of vanadium has also been detected in light from the sun and some other stars.Much of the vanadium metal being produced is now made by calcium reduction of

V2O5 in a pressure vessel. Vanadium is usually recovered as a by-product or co-prod-uct, and so world resources of the element are not really indicative of available sup-ply.

Compounds

Vanadium pentoxide (V2O5) is used as a catalyst, dye and color-fixer.

Isotopes

Naturally occurring vanadium is composed of 1 stable isotope; V-51. 15 radioisotopes have been characterized with the most stable being V-50 with a half-life of 1.4E17 years, V-49 with a half-life of 330 days, and V-48 with a half-life of 15.9735 days. All of the remaining radioactive isotopes have half-lifes that are less than 1 hour and the majority of these have half lifes that are less than 10 seconds. This element also has 1 meta state.The isotopes of vanadium range in atomic weight from 43.981 amu (V-43) to 59.959

amu (V-59). The primary decay mode before the most abundant stable isotope, V-51, is electron capture and the primary mode after is beta decay. The primary decay prod-ucts before V-51 are element 22 (titanium) isotopes and the primary products after are element 24 (chromium) isotopes.



Previous Page

Chromium

Chromium is a chemical element in the periodic table that has the symbol Cr, atomic number 24 and atomic weight of 51.9961. It is a Transition metal element.

• Name: Chromium• Symbol: Cr• Atomic number: 24• Atomic weight: 51.9961• Standard state: solid at 298 K• CAS Registry ID: 7440-47-3• Group in periodic table: 6• Group name: (none)• Period in periodic table: 4• Block in periodic table: d-block• Colour: silvery metallic• Classification: Metallic

Notable CharacteristicsChromium is a steel-gray, lustrous, hard metal that takes a high polish, is fusible with

difficulty, and is resistant to corrosion and tarnishing. The most common oxidation states of chromium are +2, +3, and +6, with +3 being the most stable. +4 and +5 are rela-tively rare. Chromium compounds of oxidation state 6 are powerful oxidants.

Applications

Uses of chromium: * In metallurgy, to impart corrosion resistance and a shiny finish: * as an alloy constituent, e.g. in stainless steel. * In chrome plating. * In anodized aluminium (literally turning the surface of an aluminium part into

ruby). * As a catalyst. * Chromite is used to make molds for the firing of bricks. * Chromium salts color glass an emerald green. * Chromium salts are used in the tanning of leather. * Chromium is what makes a ruby red, and therefore is used in producing synthetic

rubies. * The chromates and oxides are used in dyes and paints. * Potassium dichromate is a chemical reagent, used in cleaning laboratory glassware

and as a titrating agent. It is also used as a mordant (i.e. a fixing agent) for dyes in fabric. * Chromium Dioxide (CrO2) is used to manufacture magnetic tape, where its higher

coercivity than iron oxide tapes gives better performance.

HistoryIn 1761, Johann Gottlob Lehmann found an orange-red mineral in the Ural Mountains

which he named Siberian red lead. Though misidentified as a lead compound with se-lenium and iron components, the material was in fact a lead chromate (PbCrO4).In 1770, Peter Simon Pallas visited the same site as Lehmann and found a red "lead"

mineral that had very useful properties as a pigment in paints. The use of Siberian red lead as a paint pigment developed rapidly. A bright yellow made from crocoite be-came a very fashionable color.In 1797, Nicolas-Louis Vauquelin received samples of crocoite ore. He was able to pro-

duce chromium oxide (CrO3) by mixing crocoite with hydrochloric acid. In 1798, Vau-quelin discovered that he could isolate metallic chromium by heating the oxide in a charcoal oven. He was also able to detect traces of chromium in precious gems, such as ruby, or emerald.During the 1800s chromium was primarily used as a component of paints but now the

primary use (85%) is for metal alloys, with the remainder used in the chemical indus-try and refractory and foundry industries. Chromium was named based on the Greek word "chroma" meaning color, because of the many colorful compounds made from it.

Biological RoleTrivalent chromium is an essential trace metal and is required for the proper metab-

olism of sugar in humans. Chromium deficiencies can affect the potency of insulin in regulating sugar balance. Unlike other essential trace metals, chromium has not been found in a metalloprotein with biological activity. Therefore, the functional basis for the chromium requirement in the diet remains unexplained.

OccurrenceChromium is mined as chromite (FeCr2O4) ore. Chromium is obtained commercially

by heating the ore in the presence of aluminium or silicon. Roughly half the chromite ore in the world is produced in South Africa. Kazakhstan, India and Turkey are also substantial producers. Untapped chromite deposits are plentiful, but geographical-ly concentrated in Kazakhstan and southern Africa. Approximately 15 million tons of marketable chromite ore were produced in 2000, and converted into approximately 4 million tons of ferro-chrome with an approximate market value of 2.5 billion US dol-lars.Though native chromium deposits are rare, some native chromium metal has been

discovered. The Udachnaya Mine in Russia produces samples of the native metal. This mine is a kimberlite pipe rich in diamonds, and the reducing environment so provided helped produce both elemental chromium and diamond.


Previous Page

CompoundsPotassium dichromate is a powerful oxidizing agent and is the preferred compound

for cleaning laboratory glassware of any possible organics. Chrome green is the green oxide of chromium, Cr2O3, used in enamel painting, and glass staining. Chrome yellow is a brilliant yellow pigment, PbCrO4, used by painters.Chromic acid has the hypothetical structure H2CrO4. Neither chromic nor dichromic

acid is found in nature, but their anions are found in a variety of compounds. Chromi-um trioxide, CrO3, the acid anhydride of chromic acid, is sold industrially as "chromic acid".

IsotopesNaturally occurring chromium is composed of 3 stable isotopes; 52-Cr, 53-Cr, and 54-

Cr with 52-Cr being the most abundant (83.789% natural abundance). 19 radioisotopes have been characterized with the most stable being 50-Cr with a half-life of (more than) 1.8E17 years, and 51-Cr with a half-life of 27.7025 days. All of the remaining ra-dioactive isotopes have half-lifes that are less than 24 hours and the majority of these have half lifes that are less than 1 minute. This element also has 2 meta states.Chromium-53 is the radiogenic decay product of 53Mn. Chromium isotopic contents

are typically combined with manganese isotopic contents and have found application in isotope geology. Mn-Cr isotope ratios reinforce the evidence from 26Al and 107Pd for the early history of the solar system. Variations in 53Cr/52Cr and Mn/Cr ratios from several meteorites indicate an initial 53Mn/55Mn ratio that suggests Mn-Cr iso-tope systematics must result from in-situ decay of 53Mn in differentiated planetary bodies. Hence 53Cr provides additional evidence for nucleosynthetic processes imme-diately before coalescence of the solar system.The isotopes of chromium range in atomic weight from 43 amu (43-Cr) to 67 amu (67-

Cr). The primary decay mode before the most abundant stable isotope, 52-Cr, is elec-tron capture and the primary mode after is beta decay.


Manganese

Manganese is a chemical element in the periodic table that has the symbol Mn, atom-ic number 25 and atomic weight of 54.938049. It is a Transition metal element.

• Name: Manganese• Symbol: Mn• Atomic number: 25• Atomic weight: 54.938049• Standard state: solid at 298 K• CAS Registry ID: 7439-96-5• Group in periodic table: 7• Group name: (none)• Period in periodic table: 4• Block in periodic table: d-block• Colour: silvery metallic• Classification: Metallic


Manganese is a gray-white metal, resembling iron. It is a hard metal and is very brit-tle, fusible with difficulty, but easily oxidized. Manganese metal is ferromagnetic only after special treatment. The most common oxidation states of manganese are +2, +3, +4, +6 and +7, though oxidation states from +1 to +7 are observed. Mn2+ often competes with Mg2+ in biological systems, and manganese compounds where manganese is in oxidation state +7 are powerful oxidizing agents.

Applications

Manganese is essential to iron and steel production by virtue of its sulfur-fixing, de-oxidizing, and alloying properties. Steelmaking, including its ironmaking component, has accounted for most manganese demand, presently in the range of 85% to 90% of the total demand. Among a variety of other uses, manganese is a key component of low-cost stainless steel formulations and certain widely used aluminium alloys.Manganese (IV) oxide is used in the original type of dry cell batteryManganese dioxide is also used as a catalyst. Manganese is used to decolorize glass

(removing the greenish tinge that presence of iron produces) and, in higher concen-tration, make violet-colored glass.


Previous Page

Manganese oxide is a brown pigment that can be used to make paint and is a com-ponent of natural umber. Potassium permanganate is a potent oxidizer and used in chemistry and in medicine as disinfectant agent.The overall level and nature of manganese use in the United States is expected to

remain about the same in the near term. No practical technologies exist for replacing manganese with other materials or for using domestic deposits or other accumula-tions to reduce the complete dependence of the United States on other countries for manganese ore. Substitutes: Manganese has no satisfactory substitute in its major applications.

HistoryManganese was in use in prehistoric times. Paints that were pigmented with manga-

nese dioxide can be traced back 17,000 years. The Egyptians and Romans used manga-nese compounds in glass-making, to either remove color from glass or add color to it. Manganese can be found in the iron ores used by the Spartans. Some speculate that the exceptional hardness of Spartan steels derives from the inadvertent production of an iron-manganese alloy.In the 17th century, the German chemist Johann Glauber first produced permanga-

nate, a useful laboratory reagent. By the mid 18th century, manganese oxide was in use in the manufacture of chlorine. The Swedish chemist Scheele was the first to rec-ognize that manganese was an element, and his colleague, Johan Gottlieb Gahn, iso-lated the pure element in 1774 by reduction of the dioxide with carbon. Around the beginning of the 19th century, scientists began exploring the use of manganese in steelmaking, with patents being granted for its use at the time. In 1816, it was noted that adding manganese to iron made it harder, without making it any more brittle.

Biological RoleManganese is an essential trace nutrient in all forms of life. The classes of enzymes

that have manganese cofactors are very broad and include such classes as oxidore-ductases, transferases, hydrolases, lyases, isomerases, ligases, lectins, and integrins. The best known manganese containing polypeptides may be arginase, Mn containing superoxide dismutase, and the diphtheria toxin.

OccurrenceLand-based resources are large but irregularly distributed; those of the United

States are very low grade and have potentially high extraction costs. South Africa and Ukraine account for more than 80% of the world's identified resources; South Africa accounts for more than 80% of the total exclusive of China and Ukraine.US Import Sources (1998-2001): Manganese ore: Gabon, 70%; South Africa, 10%; Aus-

tralia, 9%; Mexico, 5%; and other, 6%. Ferromanganese: South Africa, 47%; France, 22%; Mexico, 8%; Australia, 8%; and other, 15%. Manganese contained in all manganese im-ports: South Africa, 31%; Gabon, 21%; Australia, 13%; Mexico, 8%; and other, 27%. Man-ganese is mined in Burkina Faso.Vast quantities of manganese exist in manganese nodules on the ocean floor. At-

tempts to find economically viable methods of harvesting manganese nodules were abandoned in the 1970s.

CompoundsPotassium permanganate, also called Condy's crystals, is a commonly used laborato-

ry reagent because of its oxidizing properties and finds use as a topical medicine (for example, in the treatment of fish diseases).Manganese dioxide is used in dry cells, and can be used to decolorize glass that is

polluted by trace amounts of iron. Manganese compounds can color glass an amethyst color, and is responsible for the color of true amethyst. Manganese dioxide is also used in the manufacture of oxygen and chlorine, and in drying black paints.

IsotopesNaturally occurring manganese is composed of 1 stable isotope; 55-Mn. 18 radioiso-

topes have been characterized with the most stable being 53-Mn with a half-life of 3.7 million years, 54-Mn with a half-life of 312.3 days, and 52-Mn with a half-life of 5.591 days. All of the remaining radioactive isotopes have half lives that are less than 3 hours and the majority of these have half lives that are less than 1 minute. This ele-ment also has 3 meta states.Manganese is part of the iron group of elements which are thought to be synthesized

in large stars shortly before supernova explosion. Manganese-53 decays to 53Cr with a half-life of 3.7 million years. Because of its relatively short half-life, 53Mn is an ex-tinct radionuclide. Manganese isotopic contents are typically combined with chromi-um isotopic contents and have found application in isotope geology. Mn-Cr isotopic ratios reinforce the evidence from 26Al and 107Pd for the early history of the solar system. Variations in 53Cr/52Cr and Mn/Cr ratios from several meteorites indicate an initial 53Mn/55Mn ratio that suggests Mn-Cr isotopic systematics must result from in-situ decay of 53Mn in differentiated planetary bodies. Hence 53Mn provides addi-tional evidence for nucleosynthetic processes immediately before coalescence of the solar system.The isotopes of manganese range in atomic weight from 46 amu (46-Mn) to 65 amu

(65-Mn). The primary decay mode before the most abundant stable isotope, 55-Mn, is electron capture and the primary mode after is beta decay.



Previous Page

IronIron is a chemical element in the periodic table that has the symbol Fe, atomic num-

ber 26 and atomic weight of 55.845.. Iron is a group 8 and period 4 a Transition metal.

• Name: Iron• Symbol: Fe• Atomic number: 26• Atomic weight: 55.845• Standard state: solid at 298 K• CAS Registry ID: 7439-89-6• Group in periodic table: 8• Group name: (none)• Period in periodic table: 4• Block in periodic table: d-block• Colour: lustrous, metallic, greyish tinge• Classification: Metallic

Notable CharacteristicsA typical iron atom has 56 times the mass of a typical hydrogen atom. Iron is the most

abundant metal, and is believed to be the tenth most abundant element, in the uni-verse. Iron is also the most abundant (by mass, 34.6%) element making up the Earth; the concentration of iron in the various layers of the Earth ranges from high at the inner core to about 5% in the outer crust; it is possible the Earth's inner core consists of a single iron crystal although it is more likely to be a mixture of iron and nickel; the large amount of iron in the Earth is thought to contribute to its magnetic field. Its symbol Fe is an abbreviation of ferrum, the Latin word for iron.Iron is a metal extracted from iron ore, and is hardly ever found in the free (elemen-

tal) state. In order to obtain elemental iron, the impurities must be removed by chem-ical reduction. Iron is used in the production of steel, which is not an element but an alloy, a solution of different metals (and some non-metals, particularly carbon).The nucleus of iron has the highest binding energy per nucleon, so it is the heavi-

est element that is produced exothermically through fusion and the lightest through fission. When a star that has sufficient mass to produce iron does so, it can no longer produce energy in its core and a supernova will ensue.Cosmological models with an open universe predict that there will be a phase where

as a result of slow fusion and fission reactions, everything will become iron.

Applications

Iron is the most used of all the metals, comprising 95 percent of all the metal ton-nage produced worldwide. Its combination of low cost and high strength make it indispensable, especially in applications like automobiles, the hulls of large ships, and structural components for buildings.

Steel is the best known alloy of iron, and some of the forms that iron takes include: * Pig iron has 4% - 5% carbon and contains varying amounts of contaminants such

as sulfur, silicon and phosphorus. Its only significance is that of an intermediate step on the way from iron ore to cast iron and steel. * Cast iron contains 2% - 3.5% carbon and small amounts of manganese. Contami-

nants present in pig iron that negatively affect the material properties, such as sul-fur and phosphorus, have been reduced to an acceptable level. It has a melting point in the range of 1420 - 1470 K, which is lower than either of its two main components, and makes it the first product to be melted when carbon and iron are heated togeth-er. It is extremely strong, hard and brittle. Working cast iron, even white hot cast iron, tends to break the object. * Carbon steel contains between 0.5% and 1.5% carbon, with small amounts of man-

ganese, sulfur, phosphorus, and silicon. * Wrought iron contains less than 0.5% carbon. It is a tough, malleable product, not

as fusible as pig iron. It has a very small amount of carbon, a few tenths of a percent. If honed to an edge, it loses it quickly. * Alloy steels contain varying amounts of carbon as well as other metals, such as

chromium, vanadium, molybdenum, nickel, tungsten, etc. * Iron (III) oxides are used in the production of magnetic storage in computers.

They are often mixed with other compounds, and retain their magnetic properties in solution.

History

The first signs of use of iron come from the Sumerians and the Egyptians, where around 4000 BC, small items, such as the tips of spears and ornaments, were being fashioned from iron recovered from meteorites. Because meteorites fall from the sky some linguists have conjectured that the English word iron, which has cognates in many northern and western European languages, derives from the Etruscan aisar which means "the gods".By 3000 BC to 2000 BC, increasing numbers of smelted iron objects (distinguish-

able from meteoric iron by the lack of nickel in the product) appear in Mesopotamia, Anatolia, and Egypt. However, their use appears to be ceremonial, and iron was an expensive metal, more expensive than gold. In The Illiad, weaponry is mosty bronze, but iron ingots are used for trade. Some resources suggest that iron was being cre-ated then as a by-product of copper refining, as sponge iron, and was not reproduc-ible by the metallurgy of the time. By 1600 BC to 1200 BC, iron was used increasingly in the Middle East, but did not supplant the dominant use of bronze.In the period from the 12th to 10th century BC, there was a rapid transition in the

Middle East from bronze to iron tools and weapons. The critical factor in this tran-


Previous Page

sition does not appear to be the sudden onset of a superior ironworking technology, but instead the disruption of the supply of tin. This period of transition, which oc-curred at different times in different parts of the world, is the ushering in of an age of civilization called the Iron Age.Concurrent with the transition from bronze to iron was the discovery of carburiza-

tion, which was the process of adding carbon to the irons of the time. Iron was recov-ered as sponge iron, a mix of iron and slag with some carbon and/or carbide, which was then repeatedly hammered and folded over to free the mass of slag and oxidise out carbon content, so creating the product wrought iron. Wrought iron was very low in carbon content and was not easily hardened by quenching. The people of the Mid-dle East found that a much harder product could be created by the long term heating of a wrought iron object in a bed of charcoal, which was then quenched in water or oil. The resulting product, which had a surface of steel, was harder and less brittle than the bronze it began to replace.In China the first irons used were also meteoric iron, with archeological evidence

for items made of wrought iron appearing in the northwest, near Xinjiang, in the 8th century BC. These items were made of wrought iron, created by the same processes used in the Middle East and Europe, and were thought to be imported by non-Chinese people.In the later years of the Zhou Dynasty (ca 550 BC), a new iron manufacturing capa-

bility began because of a highly developed kiln technology. Producing blast furnaces capable of temperatures exceeding 1300 K, the Chinese developed the manufacture of cast, or pig iron.If iron ores are heated with carbon to 1420 - 1470 K, a molten liquid is formed, an alloy

of about 96.5% iron and 3.5% carbon. This product is strong, can be cast into intricate shapes, but is too brittle to be worked, unless the product is decarburized to remove most of the carbon. The vast majority of Chinese iron manufacture, from the Zhou dy-nasty onward, was of cast iron. Iron, however, remained a pedestrian product, used by farmers for hundreds of years, and did not really affect the nobility of China until the Qin dynasty (ca 221 BC).Cast iron development lagged in Europe, as the smelters could only achieve tempera-

tures of about 1000 K. Through a good portion of the Middle Ages, in Western Europe, iron was still being made by the working of sponge iron into wrought iron. Some of the earliest casting of iron in Europe occurred in Sweden, in two sites, Lapphyttan and Vinarhyttan, between 1150 and 1350 AD. There are suggestions by scholars that the practice may have followed the Mongols across Russia to these sites, but there is no clear proof of this hypothesis. In any event, by the late fourteenth century, a market for cast iron goods began to form, as a demand developed for cast iron cannonballs.Early iron smelting (as the process is called) used charcoal as both the heat source

and the reducing agent. In 18th century England, wood supplies ran down and coke, a fossil fuel, was used as an alternative. This innovation by Abraham Darby supplied the energy for the Industrial Revolution.

Occurrence

Iron is one of the more common elements on Earth, making up about 5% of the Earth's crust. Most of this iron is found in various iron oxides, such as the minerals hematite, magnetite, and taconite. The earth's core is believed to consist largely of a metallic iron-nickel alloy. About 5% of the meteorites similarly consist of iron-nickel alloy. Al-

though rare, these are the major form of natural metallic iron on the earth's surface.Industrially, iron is extracted from its ores, principally hematite (nominally Fe2O3)

and magnetite (Fe3O4) by reduction with carbon in a blast furnace at temperatures of about 2000Â°C. In a blast furnace, iron ore, carbon in the form of coke, and a flux such as limestone are fed into the top of the furnace, while a blast of heated air is forced into the funace at the bottom. In the furnace, the coke reacts with oxygen in the air blast to produce carbon monoxide: 2 C + O2 ? 2 CO The carbon monoxide reduc-es the iron ore (in the chemical equation below, hematite) to molten iron, becoming carbon dioxide in the process: 3 CO + Fe2O3 ? 2 Fe + 3 CO2 The flux is present to melt impurities in the ore, principally silicon dioxide sand and other silicates. Common fluxes include limestone (principally calcium carbonate) and dolomite (magnesium carbonate). Other fluxes may be used depending on the impurities that need to be re-moved from the ore. In the heat of the furnace the limestone flux decomposes to cal-cium oxide (quicklime): CaCO3 ? CaO + CO2 Then calcium oxide combines then with silicon dioxide to form a slag. CaO + SiO2 ? CaSiO3The slag melts in the heat of the furnace, which silicon dioxide would not have. In

the bottom of the furnace, the molten slag floats on top of the more dense liquid iron, and spouts in the side of the furnace may be opened to drain off either the iron or the slag. The iron, once cooled, is called pig iron, while the slag can be used as a material in road construction or to improve mineral-poor soils for agriculture.Approximately 1100Mt (million tons) of iron ore was produced in the world in 2000,

with a gross market value of approximately 25 billion US dollars. While ore production occurs in 48 countries, the five largest producers were China, Brazil, Australia, Rus-sia and India, accounting for 70% of world iron ore production. The 1100Mt of iron ore was used to produce approximately 572Mt of pig iron.

Compounds

Common oxidation states of iron include: * The Iron (II) state, Fe2+, previously ferrous * The Iron (III) state, Fe3+, previously ferric * The Iron (IV) state, Fe4+, previously ferryl, stabilized in some enzymes (e.g. peroxi-

dases) * Iron (VI) is also known, if rare. In the form of potassium-ferrate (K2FeO4) it is a se-

lective oxidizer for primary alcohols. The solid is only stable under vacuum and dark purple in both (caustic) solution and as a solid. * Iron carbide Fe3C is known as cementite. * see also iron oxide

Biological Role

Iron is essential to all organisms, except for a few bacteria. Animals incorporate iron into the heme complex, an essential component of proteins involved in redox reac-tions, including respiration. Inorganic iron is also found in the iron-sulfur clusters of many enzymes, such as nitrogenase (Synthesis of ammonia from nitrogen and hy-drogen) and hydogenase. A class of non-heme-iron enzymes is responsible for a wide range of functions within several life forms, such as methane monooxygenase (oxidiz-es methane to methanol), ribonucleotide reductase (reduces ribose to desoxyribose; DNA biosynthesis), hemerythrins (oxygen transport and fixation in marine inverte-


Previous Page

brae) and purple acid phosphatase (hydrolysis of phosphate esters).Good sources of dietary iron include meat, fish, poultry, lentils, beans, spinach, tofu,

chickpeas and black-eyed peas. Iron provided by dietary supplements is often found as Iron (II) fumarate.

Isotopes

Iron has four naturally-occurring stable isotopes, 54Fe, 56Fe, 57Fe and 58Fe. The rel-ative abundances of the Fe isotopes in nature are approximately 54Fe (5.8%), 56Fe (91.7%), 57Fe (2.2%) and 58Fe (0.3%). 60Fe is an extinct radionuclide which had a long half-life (1.5 Myr). Much of the past work on measuring the isotopic composition of Fe has centered on determining 60Fe variations due to processes accompanying nucleo-synthesis (i.e., meteorite studies) and ore formation. The isotope 56Fe is of particular interest to nuclear scientists as it represents the most stable nucleus possible. It is not possible to perform fission or fusion on 56Fe and still liberate energy. This does not hold true for any other element. In phases of the meteorites Semarkona und Chervony Kut a correlation between the concentration of 60Ni, the daughter product of 60Fe, and the abundance of the stable iron isotopes could be found which is evidence for the existence of 60Fe at time formation of solar system. Possibly the energy released by the decay of 60Fe contributed, together with the energy released by decay of the radionuclide 26Al, to the remelting and differentiation of asteroids after their forma-tion 4.6 billion years ago. The abundance of 60Ni present in extraterrestrial material may also provide further insight into the origin of the solar system and its early histo-ry. Of the stable isotopes, only 57Fe has a nuclear spin. For this reason, 57Fe has appli-cation as a spin isotope in chemistry and biochemistry.


Cobalt

Cobalt is a chemical element in the periodic table that has the symbol Co and atomic number 27 and atomic weight of 58.933195 It is a Metallic element.

• Name: Cobalt• Symbol: Co• Atomic number: 27• Atomic weight: 58.933195• Standard state: solid at 298 K• CAS Registry ID: 7440-48-4• Group in periodic table: 9• Group name: (none)• Period in periodic table: 4• Block in periodic table: d-block• Colour: lustrous, metallic, greyish tinge• Classification: Metallic


Cobalt is a hard ferromagnetic silver-white element. The Curie temperature is of 1388 K with 1.6~1.7 Bohr magnetons per atom. It is frequently associated with nickel, and both are characteristic ingredients of meteoric iron. Mammals require small amounts of cobalt salts. Cobalt-60, an artificially produced radioactive isotope of cobalt, is an important radioactive tracer and cancer-treatment agent. Cobalt has a relative per-meability two thirds that of iron. Metallic cobalt commonly presents a mixture of two crystallographic structures hcp and fcc with a transition temperature hcp->fcc of 722 K. Common oxidation states of cobalt include +2, and +3, though +1 is also seen

Applications

Alloys, such as: * Superalloys, for parts in gas turbine aircraft engines. * Corrosion- and wear-resistant alloys. * High-speed steels. * Cemented carbides (also called hard metals) and diamond tools. ; * Magnets and magnetic recording media. * Alnico magnets.


Previous Page

* Catalysts for the petroleum and chemical industries. * Electroplating because of its appearance, hardness, and resistance to oxidation. * Drying agents for paints, varnishes, and inks. * Ground coats for porcelain enamels.* Pigments (cobalt blue and cobalt green). * Battery electrodes. * Steel-belted radial tires. * Cobalt-60 has multiple uses as a gamma ray source: * It is used in radiotherapy.* It is used in radiation treatment of foods for sterilization (cold pasteurization). * It is used in industrial radiography to detect structural flaws in metal parts.Co-60 is useful as a gamma ray source partially because it can be produced in known

quantity, and very large amounts by simply exposing natural cobalt to neutrons in a reactor for a given time.

Use in Medicine

Cobalt-60 (Co-60 or 60Co) is a radioactive metal that is used in radiotherapy. It pro-duces two gamma rays with energies of 1.17 MeV and 1.33 MeV. The 60Co source is about 2cm in diameter and as a result produces a geometric penumbra, making the edge of the radiation field fuzzy. The metal has the unfortunate habit of producing a fine dust, causing problems with radiation protection. The 60Co source is useful for about 5 years but even after this point is still very radioactive, and so cobalt machines have fallen from favor in the Western world where linacs are common. The first 60Co therapy machine (the "cobalt bomb") was built and first used in Canada. In fact the first machine is on display in the Saskatoon Cancer Centre â€“ look up when entering the lobby. The second machine is out beside the walkway into the Centre.

History

Cobalt was known in ancient times through its compounds, which would color glass a rich blue.George Brandt (1694-1768) is credited with the discovery of cobalt. The date of discov-

ery varies depending on the source, but is between 1730 and 1737. He was able to show that cobalt was the source of the blue color in glasses, which previously had been attributed to the bismuth found with cobalt. During the 19th century, cobalt blue was produced at the Norwegian BlaafarvevÃ¦rket (70-80 % of world production), led by the Prussian industrialist Benjamin Wegner.In 1938, John Livingood and Glenn Seaborg discovered cobalt-60. The word cobalt

comes from the German kobalt or kobold, meaning evil spirit, the metal being so called by miners, because it was poisonous and troublesome (it polluted and degraded the other mined elements, like nickel).

Biological Role

Cobalt in small amounts is essential to many living organisms, including humans. Having 0.13 to 0.30 parts per million of cobalt in soils markedly improves the health of grazing animals. Cobalt is a central component of the vitamin cobalamin, or vitamin

B-12.

Occurrence

Cobalt is not found as a free metal and is generally found in the form of ores. Cobalt is usually not mined alone, and tends to be produced as a by-product of nickel and copper mining activities. The main ores of cobalt are cobaltite, erythrite, glaucodot, and skutterudite. The world's major producers of cobalt are DRC, mainland China, Zambia, Russia and Australia

Compounds

Due to the various oxidation states, there is an abundant number of compounds. Oxides are antiferromagnetic at low temperature CoO (Neel temperature: 291 K) and Co3O4 (Neel temperature: 40 K).

Isotopes

Naturally occurring cobalt is composed of 1 stable isotope, 59-Co (59Co). 22 radio-isotopes have been characterized with the most stable being 60Co with a half-life of 5.2714 years, 57-Co (57Co) with a half-life of 271.79 days, and 56-Co (56Co) with a half-life of 77.27 days, and 58-Co (58Co) with a half life of 70.86 days. All of the remaining ra-dioactive isotopes have half-lifes that are less than 18 hours and the majority of these have half lives that are less than 1 second. This element also has 4 meta states, all of which have half lives less than 15 minutes.The isotopes of cobalt range in atomic weight from 50 amu (50Co) to 73 amu (73Co).

The primary decay mode before the most abundant stable isotope, 59Co, is electron capture and the primary mode after is beta decay. The primary decay products before 59Co are element 26 (iron) isotopes and the primary products after are element 28 (nickel) isotopes.



Previous Page

Nickel

Nickel is a chemical element in the periodic table that has the symbol Ni, atomic num-ber 28 and atomic weight of 58.6934. It is a Transition metal element.

• Name: Nickel• Symbol: Ni• Atomic number: 28• Atomic weight: 58.6934• Standard state: solid at 298 K• CAS Registry ID: 7440-02-0• Group in periodic table: 10• Group name: (none)• Period in periodic table: 4• Block in periodic table: d-block• Colour: lustrous, metallic, silvery tinge• Classification: Metallic


Nickel is silvery white metal that takes on a high polish. It belongs to the iron group, and is hard, malleable, and ductile. It occurs combined with sulfur in millerite, with arsenic in the mineral niccolite, and with arsenic and sulfur in nickel glance.On account of its permanence in air and inertness to oxidation, it is used in the small-

er coins, for plating iron, brass, etc., for chemical apparatus, and in certain alloys, as german silver. It is magnetic, and is very frequently accompanied by cobalt, both be-ing found in meteoric iron. It is chiefly valuable for the alloys it forms.Nickel is one of the five ferromagnetic elements. Because of the precise alloy used,

the US "nickel" coin is not ferromagnetic, while the Canadian coin of the same name is.The most common oxidation state of nickel is +2, though 0, +1 and +3 Ni complexes are

observed.Nickel is found as a constituent in most meteorites and often serves as one of the cri-

teria for distinguishing a meteorite from other minerals. Iron meteorites, or siderites, may contain iron alloyed with from 5 to nearly 20% nickel. The USA 5-cent coin (whose nickname is “nickel”) contains just 25% nickel. Nickel is a silvery white metal that takes on a high polish. It is hard, malleable, ductile, somewhat ferromagnetic, and a fair conductor of heat and electricity.Nickel carbonyl, [Ni(CO)4], is an extremely toxic gas and exposure should not exceed

0.007 mg M-3.

Physical Properties

Melting points of the chemical elements displayed on a miniature periodic table-Melting point: 1728 [or 1455 °C (2651 °F)] K Boiling points of the chemical elements displayed on a miniature periodic table-

Boiling point: 3186 [or 2913 °C (5275 °F)] K Density of the chemical elements displayed on a miniature periodic tableDensity of

solid: 8908 kg m-3

Applications

About 65% of the nickel consumed in the Western World is used to make austenitic stainless steel. Another 12% goes into superalloys. The remaining 23% of consumption is divided between alloy steels, rechargeable batteries, catalysts and other chemicals, coinage, foundry products, and plating.

Applications include: * Stainless steel and other corrosion-resistant alloys. * Nickel steel is used for armor plates and burglar-proof vaults. * The alloy Alnico is

used in magnets. * Mu-metal has an especially high magnetic permeability, and is used to screen mag-

netic fields. * Monel metal is a steel alloy highly resistant to corrosion, used for ship propellors,

kitchen supplies, and chemical industry plumbing * Smart wire, or shape memory alloys, are used in robotics. * Rechargable batteries, such as nickel metal hydride batteries and nickel cadmium

batteries. * Coinage. In the United States and Canada, nickel is used in five-cent coins called

nickels. See also clad. * In electroplating. * In crucibles for chemical laboratories. * Finely divided nickel is a catalyst for hydrogenating vegetable oils.

History

Nickel use is ancient, and can be traced back as far as 3500 BC. Bronzes from what is now Syria had a nickel content of up to two percent. Further, there are Chinese man-uscripts suggesting that "white copper" (e.g. paitung) was used in the Orient between 1400 and 1700 BC. However, because the ores of nickel were easily mistaken for ores of silver, any understanding of this metal and its use dates to more contemporary times.Minerals containing nickel (e.g. kupfernickel, or false copper) were of value for color-

ing glass green. In 1751, Baron Axel Frederik Cronstedt was attempting to extract cop-per from kupfernickel (now called niccolite), and obtained instead a white metal that he called nickel.The first nickel coin of the pure metal was made in 1881.


Previous Page

Biological Role

Many but not all hydrogenases contain nickel in addition to iron-sulfur clusters. Nickel centers are a common element in those hydrogenases whose function is to ox-idize rather than evolve hydrogen. The nickel center appears to undergo changes in oxidation state, and evidence has been presented that the nickel center might be the active site of these enzymes.A nickel-tetrapyrrole coenzyme, Co-F430, is present in the methyl CoM reductase and

in methanogenic bacteria. The tetrapyrrole is intermediate in structure between por-phyrin and corrin. Changes in redox state, as well as changes in nickel coordination, have recently been observed.There is also a nickel-containing carbon monoxide dehydrogenase. Little is known

about the structure of the nickel site.

Occurrence

The bulk of the nickel mined comes from two types of ore deposits. The first are lat-erites where the principal ore minerals are nickeliferous limonite [(Fe,Ni)O(OH)] and garnierite (a hydrous nickel silicate). The second are magmatic sulfide deposits where the principal ore mineral is pentlandite [(Ni,Fe)9S8]. In terms of supply, the Sudbury region of Ontario, Canada, produces about 30 percent of the world's supply of nickel. Other deposits are found in Russia, New Caledonia, Australia, Cuba, and Indonesia. However, most of the nickel on Earth is believed to be concentrated in the planet's core.

Compounds

* Kamacite, a naturally occurring alloy of iron and nickel.

Isotopes

Naturally occurring nickel is composed of 5 stable isotopes; 58-Ni, 60-Ni, 61-Ni, 62-Ni and 64-Ni with 58-Ni being the most abundant (68.077% natural abundance). 18 ra-dioisotopes have been characterized with the most stable being 59-Ni with a half-life of 76,000 years, 63-Ni with a half-life of 100.1 years, and 56-Ni with a half-life of 6.077 days. All of the remaining radioactive isotopes have half-lifes that are less than 60 hours and the majority of these have half lifes that are less than 30 seconds. This ele-ment also has 1 meta state.Nickel-56 is produced in large quantities in type II supernova and the shape of the

light curve of these supernova corresponds to the decay of nickel-56 to cobalt-56 and then to iron-56.Nickel-59 is a long-lived cosmogenic radionuclide with a half-life of 76,000 years.

59Ni has found many applications in isotope geology. 59Ni has been used to date the terrestrial age of meteorites and to determine abundances of extraterrestrial dust in ice and sediment. Nickel-60 is the daughter product of the extinct radionuclide 60Fe (half-life = 1.5 Myr). Because the extinct radionuclide 60Fe had such a long half-life, its persistence in solar_system materials at high enough concentrations may have gener-ated observable variations in the isotopic composition of 60Ni. Therefore, the abun-

dance of 60Ni present in extraterrestrial material may provide insight into the origin of the solar system and its early history.The isotopes of nickel range in atomic weight from 52 amu (52-Ni) to 74 amu (74-Ni).



Previous Page

Copper

Copper is a chemical element in the periodic table that has the symbol Cu, atomic number 29 and atomic weight of 63.546. It is a Transition metal element.

• Name: Copper• Symbol: Cu• Atomic number: 29• Atomic weight: 63.546• Standard state: solid at 298 K• CAS Registry ID: 7440-50-8• Group in periodic table: 11• Group name: Coinage metal• Period in periodic table: 4• Block in periodic table: d-block• Classification: Metallic


Copper is a reddish-coloured metal, with a high electrical and thermal conductivity (among pure metals at room temperature, only silver has a higher electrical conduc-tivity). Copper may well be the oldest metal in use, as copper artifacts dating to 8700 BC have been found. Besides being part of various ores, copper can be found in the metallic form ( i.e. native copper) in some locations.In Greek times, the metal was known by the name Chalkos. In Roman times, it became

known as aes Cyprium, because so much of it was mined in Cyprus. From this, the phrase was simplified to cuprum and then Anglicized into the English copper..

Applications

Copper is malleable and ductile, and is used extensively, in products such as: * Copper wire. * Copper plumbing. * Doorknobs and other fixtures in houses. * Statuary: The Statue of Liberty, for example, contains 179,000 pounds of copper. * Electromagnets. * Motors, esp electromagnetic motors. * Watt's steam engine.

* Electrical relays , electrical busbars and electrical switches. * Vacuum tubes, cathode ray tubes, and the magnetrons in microwave ovens. * Wave guides for microwave radiation. * There is increasing use of copper in integrated circuits, replacing aluminium be-

cause of its superior conductivity. * As a component of coins. * In cookware, such as frying pans. * Most flatware (knives, forks, spoons) contains some copper (nickel silver). * Sterling silver, if it is to be used in dinnerware, must contain a few percent copper. * As a component in ceramic glazes, and to color glass. * Musical instruments, especially brass instruments. * As a biostatic surface in hospitals, and to line parts of ships to protect against bar-

nacles and mussels. * Compounds, such as Fehling's solution, have applications in chemistry. * Copper (II) sulfate is used as a poison and a water purifier.

History

Copper was known to some of the oldest civilizations on record, and has a history of use that is at least 10,000 years old. A copper pendant was found in what is now northern Iraq that dates to 8700 BC. By 5000 BC there are signs of copper smelting, the refining of copper from simple copper oxides such as malachite or azurite. The earliest signs of gold use, by contrast, appear around 4000 BC.There are copper and bronze artifacts from Sumerian cities that date to 3000 BC, and

Egyptian artifacts in copper and copper alloyed with tin nearly as old. In one pyramid, a copper plumbing system was found that is 5000 years old. The Egyptians found that adding a small amount of tin made the metal easier to cast, so bronze alloys are found in Egypt almost as soon as copper is found. Use of copper in ancient China dates to at least 2000 BC. By 1200 BC excellent bronzes were being made in China. Note that these dates are affected by wars and conquest, as copper is easily melted down and reused. In Europe, Oetzi the Iceman, a well preserved male dated to 3200 BC, was found with a copper tipped axe whose metal was 99.7% pure. High levels of arsenic in his hair sug-gests he was involved in copper smelting.The use of bronze was so pervasive in a certain era of civilization that it has been

named the Bronze Age. The transitional period in certain regions between the pre-ceding Neolithic period and the Bronze Age is termed the Chalcolithic, with some high purity copper tools being used alongside stone tools. Brass, an alloy of zinc and cop-per, was known to the Greeks but first used extensively by the Romans.Copper was associated with the goddess Aphrodite/Venus in mythology and alchemy,

owing to its lustrous beauty, its ancient use in producing mirrors, and its association with Cyprus, which was sacred to the goddess. In alchemy, the symbol for copper was also the symbol for the planet Venus.

Biological Role

Copper is essential in all higher plants and animals. Copper is found in a variety of enzymes, including the copper centers of cytochrome c oxidase, the Cu-Zn containing enzyme superoxide dismutase, and is the central metal in the oxygen carrying pig-ment hemocyanin. The blood of the horseshoe crab, Limulus polyphemus uses copper


Previous Page

rather than iron for oxygen transport.The RDA for copper in normal healthy adults is 0.9 mg/day. Copper is carried mostly

in the bloodstream on a plasma protein called ceruloplasmin. Though when copper is first absorbed in the gut it is transported to the liver bound to albumin.An inherited condition called Wilson's disease causes the body to retain copper, as it

is not excreted by the liver into the bile. This disease, if untreated, can lead to brain and liver damage.

Occurrence

Copper is found as native copper in mineral form. Minerals such as the carbonates azurite and malachite are sources of copper, as are sulfides such as chalcopyrite (CuFeS2), bornite (Cu5FeS4), covellite (CuS), chalcocite (Cu2S) and oxides like cuprite (Cu2O).

Compounds

There are numerous alloys of copper - speculum metal is a copper/tin alloy, Brass is a copper/zinc alloy, and bronze is a copper/tin alloy. Common oxidation states of cop-per include the copper (I) state, Cu+1, and copper (II) state, Cu+2.Copper carbonate is green from which arises the unique appearance of copper-clad

roofs or domes on some buildings.Copper oxides (e.g. yttrium barium copper oxide (YBa2Cu3O7-?) or YBCO) form the ba-

sis of many unconventional superconductors Other compoundscopper (II) sulfide.

Isotopes

There are two stable isotopes, 63Cu and 65Cu, along with a couple dozen radioiso-topes. The vast majority of radioisotopes have half lives on the order of minutes or less, the longest lived, 64Cu, has a half life of 12.7 hours, with two decay modes, lead-ing to two separate products.

Mining

Most copper currently is mined from large open pit mines in deposits that contain less than one percent copper. Examples include: Chuquicamata, Chile and El Chino mine in New Mexico.Copper concentrate generally contains 25 to 30 percent copper. Copper concentrate

is the resulting product after mine ore (containing less than 1 percent copper) has been crushed, milled and concentrated.Copper cathode is 99.97% copper in sheets of dimensions: 96 cm x 95 cm x 1 cm, with

a mass of about 100 kg. It a true commodity and the product deliverable to the metal exchanges in New York, London and Shanghai. A chemical specification for electrolyt-ic grade copper is ASTM B 115-00.



Previous Page

Zinc

Zinc is a chemical element in the periodic table that has the symbol Zn, atomic num-ber 30 and atomic weight of 65.409. It is a Metallic element.

• Name: Zinc• Symbol: Zn• Atomic number: 30• Atomic weight: 65.409• Standard state: solid at 298 K• CAS Registry ID: 7440-66-6• Group in periodic table: 12• Group name: (none)• Period in periodic table: 4• Block in periodic table: d-block• Colour: bluish pale grey• Classification: Metallic


Zinc is a moderately reactive metal that will combine with oxygen and other non-metals, and will react with dilute acids to release hydrogen. The one common ox-idation state of zinc is +2.

Applications

Zinc is the fourth most common metal in use, trailing only iron, aluminium, and cop-per in tons of metal produced per year. * Zinc is used to galvanize metals such as steel to prevent their corrosion. * Zinc is used in alloys such as brass, nickel silver, typewriter metal, various solder

formulas, German silver, etc. * Brass, in turn, has wide application because of its strength and corrosion resis-

tance. * Zinc is used in die castings, especially by the automobile industry. * Rolled zinc is used as part of the containers of batteries. * Zinc oxide is used as a white pigment in watercolors and paints, and as an activator

in the rubber industry. As an over-the-counter ointment, it is applied as a thin coating on the exposed skin of the face and nose to prevent dehydration and thereby protect

against sunburn in the summer and windburn in the winter. Applied thinly to a baby's diaper area (perineum) with each diaper change, it protects against rash. * Zinc chloride is used as a deodorant and as a wood preservative. * Zinc sulfide is used in luminescent pigments, for making the hands of clocks and

other items that glow in the dark. * Zinc methyl (Zn(CH3)2) is used in a number of organic syntheses. * Lotions made of calamine, a mix of Zn-(hydroxy-)carbonates and silicates, are used

to treat skin rash. * Zinc metal is included in most proprietary over-the-counter daily vitamin and

mineral preparations. Along with some other metals, it is commonly believed to pos-sess anti-oxidant properties, which protect against premature aging of the skin and muscles of the body. In larger amounts, taken as zinc alone in other proprietaries, it is believed to speed up the healing process after an injury. * Zinc gluconate glycine is taken in lozenge form as a remedy for the common cold.

History

Zinc alloys have been used for centuries, as brass goods dating to 1000-1400 BC have been found in Palestine and zinc objects with 87% zinc have been found in prehistoric Transylvania. Because of the low boiling point and chemical reactivity of this metal (isolated zinc would tend to go up the chimney rather than be captured), the true na-ture of this metal was not understood in ancient times.The manufacture of brass was known to the Romans by about 30 BC, using a tech-

nique where calamine and copper were heated together in a crucible. The zinc oxides in calamine were reduced, and the free zinc metal was trapped by the copper, forming an alloy. The resulting brass was either cast or hammered into shape.Smelting and extraction of impure forms of zinc was being accomplished as early as

AD 1000 in India and China. By the end of the 14th century, the Hindus were aware of the existence of zinc as a metal separate from the seven known to the ancients. In the West, the discovery of pure metallic zinc is most often credited to the German Andreas Marggraf, in the year 1746, though the whole story is considerably more in-volved.Descriptions of brass manufacture are found in Western Europe in the writings of Al-

bertus Magnus, c. 1248, and by the 16th century, the understanding and awareness of the new metal broadened considerably. Agricola observed, in 1546, that a white metal could be condensed and scraped off the walls of a furnace when zinc ores were smelt-ed. He added in his notes that a similar metal called "zincum" was being produced in Silesia. Paracelsus (died 1541) was the first in the West to say that that "zincum" was a new metal and that it had a separate set of chemical properties from other known metals.The upshot is that zinc was known by the time Marggraf made his discoveries and

in fact zinc had been isolated two years earlier by another chemist, Anton von Swab. However, Marggraf's reports were exhaustive and methodical and the quality of his research cemented his reputation as the discoverer of zinc. Before the discovery of the zinc sulfide flotation technique, calamine was the mineral source of zinc metal.

Biological Role

Zinc is an essential element in human beings, necessary for sustaining life. Deficien-


Previous Page

cies of zinc have marked effects on weight gain in animals. Zinc is found in insulin, zinc finger proteins, and such enzymes as superoxide dismutase.According to some sources, taking zinc tablets may provide some immunity against

colds and flu, although this is disputed. Eyesight, taste, smell and memory are also connected with zinc and a deficiency in zinc can cause malfunctions of these organs and functions.Natural food sources of zinc include oysters, red meat and poultry, beans, nuts, whole

grains, pumpkin seed or sunflower seeds. In males, zinc is important for the produc-tion of semen. Up to 5 mg of zinc is lost during ejaculation. Defiencies in zinc in males can lead to reduced sperm count and sex drive. Frequent ejaculations can lead to zinc defiency.

Abundance

Zinc is the 23rd most abundant element in the earth's crust. The most heavily mined ores tend to contain roughly 10% iron as well as 40-50% zinc. Minerals from which zinc is extracted include sphalerite, zinc blende, smithsonite, calamine, and franklinite.There are zinc mines throughout the world, with the largest producers being Austra-

lia, Canada, China, Peru and the U.S.A. Mines in Europe include Vieille Montagne in Belgium and Zinkgruvan in Sweden.

Compounds

Zinc oxide is perhaps the best known and most widely used zinc compound, as it makes a good base for white pigments in paint. It also finds industrial use in the rub-ber industry, and is sold as opaque sunscreen. A variety of other zinc compounds find use industrially, such as zinc chloride (in deodorants), zinc sulfide (in luminescent paints), and zinc methyl in the organic laboratory. Roughly one quarter of all zinc out-put is consumed in the form of zinc compounds.

Isotopes

Naturally occurring zinc is composed of the 4 stable isotopes Zn-64, Zn-66, Zn-67, and Zn-68 with 64 being the most abundant (48.6% natural abundance). 22 radioisotopes have been characterized with the most (abundant and/or stable) being Zn-65 with a half-life of 244.26 days, and Zn-72 with a half-life of 46.5 hours. All of the remaining ra-dioactive isotopes have half-lives that are less than 14 hours and the majority of these have half lives that are less than 1 second. This element also has 4 meta states.


Gallium

Gallium is a chemical element in the periodic table that has the symbol Ga, atomic number 31 and atomic weight of 69.723 It is a Metallic element.

• Name: Gallium• Symbol: Ga• Atomic number: 31• Atomic weight: 69.723• Standard state: solid at 298 K (but melts only slightly above this tem-

perature)• CAS Registry ID: 7440-55-3• Group in periodic table: 13• Group name: (none)• Period in periodic table: 4• Block in periodic table: p-block• Colour: silvery white• Classification: Metallic

A rare, soft silvery metallic poor metal, gallium is brittle at low temperatures but is liquid above room temperature and can indeed melt in the hand. It occurs in trace amounts in bauxite and zinc ores. Gallium arsenide is used as a semiconductor, most notably in light-emitting diodes (LEDs).


Very-pure gallium has a stunning silvery color and its solid metal fractures conchoid-ally like glass. Gallium metal expands by 3.1 percent when it solidifies, and therefore should not be stored in either glass or metal containers. Gallium also corrodes most other metals by diffusing into their metal lattice.Gallium is one of four metals (with caesium, mercury, and rubidium) which are liquid

at near normal room temperature, and can therefore be used in high-temperature thermometers. It is also notable for having one of the largest liquid ranges for a metal, and for having a low vapor pressure at high temperatures.This metal has a strong tendency to supercool below its melting point, thus necessi-

tating seeding in order to solidify. High-purity gallium is attacked slowly by mineral acids. The melting point temperature is very low, T=30°C, and the density is higher in the liquid state than in the crystalline state (like in the case of water; the opposite


Previous Page

effect is normally found for metals).Gallium does not crystallize in any of the simple crystal structures. The stable phase

under normal conditions is orthorhombic with 8 atoms in the conventional unit cell. Each atom has only one nearest neighbor (at a distance of 2.44Å) and six other neigh-bors within additional 0.39 Å. Many stable and metastable phases are found as func-tion of temperature and pressure.The bonding between the nearest neighbors is found to be of covalent character,

hence Ga2 dimers is seen as the fundamental building block of the crystal. The com-pound, gallium arsenide is a semiconductor commonly used in light-emitting diodes).

Applications

Analog integrated circuits are the most common application for gallium, with opto-electronic devices (mostly laser diodes and light-emitting diodes) as the second larg-est end use.

Other uses include: * Since it wets glass or porcelain, gallium is used to create brilliant mirrors. * Used widely to dope semiconductors and produce solid-state devices like transis-

tors. * Gallium readily alloys with most metals, and has been used as a component in

low-melting alloys. The plutonium pits of nuclear weapons employ an alloy with gal-lium to stabilize of the allotropes of plutonium. Much research is being devoted to gallium alloys as substitutes for mercury dental amalgams, but such compounds have yet to see wide acceptance. Gallium added in quantities up to 2% in common solders can aid wetting and flow characteristics. * Gallium is used in some high temperature thermometers, and a eutectic alloy of

gallium, indium, and tin is widely available in fever thermometers, replacing mercury. This alloy, with the trade name Galinstan, has a freezing point of -20°C. * Magnesium gallate containing impurities (such as Mn+2), is beginning to be used

in ultraviolet-activated phosphor powder.

History

Gallium (Latin Gallia meaning "France"; also gallus, meaning "cock") was discovered spectroscopically by Lecoq de Boisbaudran in 1875 by its characteristic spectrum (two violet lines) in an examination of a zinc blend from the Pyrenees. Before its discovery, most of its properties had been predicted and described by Dmitri Mendeleev (who called the hypothetical element eka-aluminium) on the basis of its position in his peri-odic table. Later in 1875, Boisbaudran obtained the free metal through the electrolysis of its hydroxide in KOH solution. He named the element after his native land of France and, in one of those multilingual puns so beloved of men of science of the early 19th century, after himself, as 'Lecoq' = the rooster, and Latin for rooster is "gallus".

Occurrence

Gallium does not exist in pure form in nature, nor are gallium compounds a primary source of extraction. It is rather found and extracted as a trace component in bauxite,

coal, diaspore, germanite, and sphalerite. The USGS estimates gallium reserves based on 50 ppm concentration in known reserves of bauxite and zinc ores. Some flue dusts from burning coal have been shown to contain as much 1.5 percent gallium.



Previous Page

GermaniumGermanium is a chemical element in the periodic table that has the symbol Ge, atom-

ic number 32 and atomic weight of 72.64. It is a Semi-metallic element.

• Name: Germanium• Symbol: Ge• Atomic number: 32• Atomic weight: 72.64• Standard state: solid at 298 K• CAS Registry ID: 7440-56-4• Group in periodic table: 14• Group name: (none)• Period in periodic table: 4• Block in periodic table: p-block• Colour: greyish white• Classification: Semi-metallic

This is a lustrous, hard, silver-white, metalloid that is chemically similar to tin. Ger-manium forms a large number of organometallic compounds and is an important semiconductor material used in transistors and photodetectors.

Notable CharacteristicsGermanium is a hard, grayish-white element that has a metallic luster and the same

crystal structure as diamond. In addition, it is important to note that germanium is a semiconductor, with electrical properties between those of a metal and an insula-tor. In its pure state, this metalloid is crystalline, brittle and retains its luster in air at room temperature. Zone refining techniques have led to the production of crystalline germanium for semiconductors that have an impurity of only one part in 1010.

HistoryIn 1871 germanium (Latin Germania for Germany) was one of the elements that Dmitri

Mendeleev predicted to exist as a missing analogue of the silicon group (Mendeleev called it "ekasilicon"). The existence of this element was proven by Clemens Winkler in 1886. This discovery was an important confirmation of Mendeleev's idea of element periodicity.The development of the germanium transistor opened the door to countless applica-

tions of solid-state electronics. From 1950 through the early 1970s, this area provided

an increasing market for germanium, but then high purity silicon began replacing germanium in transistors, diodes, and rectifiers. Silicon has superior electrical prop-erties, but requires much higher purity samples, a purity which could not be com-mercially achieved in the early days. Meanwhile, demand for germanium in fiber optics communication networks, infrared night vision systems, and polymerization catalysts increased dramatically. These end uses represented 85% of worldwide ger-manium consumption for 2000.

ApplicationsUnlike most semiconductors, germanium has a small band gap, allowing it to effi-

ciently respond to infrared light. It is therefore used in infrared spectroscopes and other optical equipment which require extremely sensitive infrared detectors. Its oxide's index of refraction and dispersion properties make germanium useful in wide-angle camera lenses and in microscope objective lenses.Germanium transistors are still used in electric guitar amplifiers by musicians who

wish to reproduce the distinctive character of amplifiers from the early Rock and roll era.The alloy silicon germanide (SiGe) is rapidly becoming an important semiconductor

material, for use in high speed integrated circuits. Circuits utilising the properties of Si-SiGe junctions can be much faster than those using silicon alone.

Other uses: Alloying agent. * Phosphor in fluorescent lamps. * A catalyst. Certain compounds of germanium have low toxicity to mammals, but

have toxic effects against certain bacteria. This property makes these compounds useful as chemotherapeutic agents.

OccurrenceThis metal is found in argyrodite (sulfide of germanium and silver); coal; germanite;

zinc ores; and other minerals.Germanium is obtained commercially from zinc ore processing smelter dust and

from the combustion by-products of certain coals. A large reserve of this element is therefore in coal sources. This metaloid can be extracted from other metals by frac-tional distillation of its volatile tetrachloride. This technique permits the production of ultra-high purity germanium.In 1997 the cost of germanium was about US$3 per gram. The yearend price for ger-

manium in 2000 was $1,150 per kilogram (or $1.15 per gram).



Previous Page

Arsenic

Arsenic is a chemical element in the periodic table that has the symbol As, atomic number 33 and atomic weight of 74.9216 It is a Semi-metallic element. In the Pnictogen group.

• Name: Arsenic• Symbol: As• Atomic number: 33• Atomic weight: 74.92160• Standard state: solid at 298 K• CAS Registry ID: 7440-38-2• Group in periodic table: 15• Group name: Pnictogen• Period in periodic table: 4• Block in periodic table: p-block• Colour: metallic grey• Classification: Semi-metallic

This is a notorious poisonous metalloid that has three allotropic forms; yellow, black and grey. Arsenic and its compounds are used as pesticides, herbicides and insecti-cides and various alloys.


Arsenic is chemically very similar to its predecessor phosphorus, so much so that it will partly substitute for it in biochemical reactions and is thus poisonous. When heated it rapidly oxidizes to arsenous oxide, which has a garlic odor. Arsenic and some arsenic compounds can also sublime upon heating, converting to gaseous form direct-ly. Elemental arsenic is found in two solid forms: yellow and gray metallic, with spe-cific gravities of 1.97 and 5.73, respectively.

Applications

Lead arsenate has been used, well into the 20th century, as a pesticide on fruit trees (resulting in neurological damage to those working the sprayers), and copper arsenate has even been recorded in the 19th century as a coloring agent in sweets. Other uses; Various agricultural insecticides and poisons., Gallium arsenide is an important semi-

conductor material, used in integrated circuits. Circuits made using the compound are much faster (but also much more expensive) than those made in silicon. Unlike silicon it is direct bandgap, and so can be used in laser diodes and LEDs to directly convert electricity into light.Arsenic trioxide has been used in hematology to treat patients with acute promy-

elocytic leukemia that are resistant to ATRA treatment. Arsenic trioxide is used in Australia for treating termite infestations in houses.. Also used in; bronzing, pyro-techny

HistoryThe word Arsenic is borrowed from the Persian word ÕNäil Zarnik meaning "yellow

orpiment". Zarnik was borrowed by Greek as arsenikon. Arsenic has been known and used in Persia and elsewhere since ancient times. It was frequently used for murder, the symptoms of arsenic poisoning being somewhat ill-defined, until the advent of the Marsh test, a sensitive chemical test for its presence. During the Bronze Age, ar-senic was often included in the bronze (mostly as an impurity), which made the alloy harder. Albertus Magnus is believed to have been the first to isolate the element in 1250. In 1649 Johann Schroeder published two ways of preparing arsenic.There is a massive epidemic of arsenic poisoning in Bangladesh. This is due to the

massive tube well drinking-water program instigated by western NGOs in the late twentieth century, who failed to test for arsenic in the groundwater. Hundreds of thousands of people are affected. It is thought to be the worst mass-poisoning in history, and possibly the worst environmental disaster in history.

OccurrenceArsenopyrite also called mispickel (FeSAs) is the most common mineral from which,

on heating, the arsenic sublimes leaving ferrous sulfide.The most important compounds of arsenic are white arsenic, its sulfide, Paris green,

calcium arsenate, and lead arsenate. Paris green, calcium arsenate, and lead arsenate have been used as agricultural insecticides and poisons. It is sometimes found na-tive, but usually combined with silver, cobalt, nickel, iron, antimony, or sulfur.In addition to the inorganic forms mentioned above, arsenic also occurs in various

organic forms in the environment. Inorganic arsenic and its compounds, upon en-tering the food chain, are progressively metabolised to a less toxic form of arsenic through a process of methylation



Previous Page

Selenium

Selenium is a chemical element in the periodic table that has the symbol Se, atomic number 34 and atomic weight of 78.96. It is a Chalcogen a Non-metallic element.

• Name: Selenium• Symbol: Se• Atomic number: 34• Atomic weight: 78.96• Standard state: solid at 298 K• CAS Registry ID: 7782-49-2• Group in periodic table: 16• Group name: Chalcogen• Period in periodic table: 4• Block in periodic table: p-block• Colour: grey, metallic lustre• Classification: Non-metallic

This is a toxic nonmetal that is chemically related to sulfur and tellurium. It occurs in several different forms but one of these is a stable gray metallike form that conducts electricity better in the light than in the dark and is used in photocells. This element is found in sulfide ores such as pyrite.


Selenium exists in a number of allotropic forms. In the powdered form, amorphous selenium is red, while the vitreous form is black. Crystalline hexagonal selenium is a metallic gray, while the monoclinic crystal is a deep red color.It also exhibits a photovoltaic effect, converting light to electricity, and a photocon-

ductive effect, electrical conductance increasing as selenium is exposed to light. Be-low its melting point, selenium is a p type semiconductor.

Applications

Selenium is an essential micronutrient in all known forms of life; it is a component of the unusual amino acid selenocysteine. Because of its photovoltaic and photoconduc-tive properties, selenium is used extensively in electronics, such as photo cells, and solar cells. Selenium is also extensively used in rectifiers.

Selenium is used to remove color from glass, as it will counteract the green color ferrous impurities impart. It also can be used to give a red color to glasses and enam-els. Selenium is used to improve the abrasion resistance in vulcanized rubbers. It also finds application in photocopying.Another use for selenium is the toning of photographs, and is sold by numerous pho-

tographic manufacturers including Kodak and Fotospeed. Its artistic use is to intensi-fy and extend the tonal range of black and white photographic images, and it can also be used for increasing the permanence of images.

History

Selenium (Latin selene meaning "Moon") was discovered in 1817 by Jons Jacob Berze-lius who found the element associated with tellurium.Growth in selenium consumption was driven by the development of new uses, includ-

ing applications in rubber compounding, steel alloying, and selenium rectifiers. By 1970, selenium in rectifiers had largely been replaced by silicon, but its use as a photo-conductor in plain paper copiers had become its leading application. During the 1980s, the photoconductor application declined (although it was still a large end-use) as more and more copiers using organic photoconductors were produced. In 1996, con-tinuing research showed a positive correlation between selenium supplementation and cancer prevention in humans, but widespread direct application of this important finding would not add significantly to demand owing to the small doses required. In the late 1990s, the use of selenium (usually with bismuth) as an additive to plumbing brasses to meet no-lead environmental standards became important.

Occurrence

Selenium occurs as selenide in many sulfide ores, such as those of copper, silver, or lead. It is obtained as a byproduct of the processing of these ores, from the anode mud of copper refineries and the mud from the lead chambers of sulfuric acid plants. These muds can be processed by a number of means to obtain free selenium.

IsotopesSelenium has 28 isotopes, of which 5 are stable.



Previous Page

Bromine

Bromine (from Gr. Bromos, meaning "stench"), is a chemical element in the periodic table that has the symbol Br, atomic number 35 and atomic weight of 79.904. It is a Non-metallic Halogen.

• Name: Bromine• Symbol: Br• Atomic number: 35• Atomic weight: 79.904• Standard state: liquid at 298 K• CAS Registry ID: 7726-95-6• Group in periodic table: 17• Group name: Halogen• Period in periodic table: 4• Block in periodic table: p-block• Colour: red-brown, metallic lustre when solid• Classification: Non-metallic

A halogen element, bromine is a red volatile liquid at room temperature which has a reactivity between chlorine and iodine. This element is harmful to human tissue in a liquid state and its vapour irritates eyes and throat.


Bromine is the only liquid non - metallic element at room temperature. It is a heavy, mobile, reddish-brown liquid, that evaporates easily at standard temperature and pressures in a red vapor (its color resembles nitrogen dioxide) that has a strong dis-agreeable odor. A halogen, bromine resembles chlorine chemically but is less active (it is more active than iodine however). Bromine is very soluble in water or carbon di-sulfide (forming a red solution). It bonds easily with many elements and has a strong bleaching action.Bromine is highly reactive and is a powerful oxidizing agent in the presence of water.

It reacts vigorously with amines, alkenes and phenols as well as aliphatic and aromat-ic hydrocarbons, ketones and acids (these are brominated by either addition or sub-stitution). With many of the metals and elements, anhydrous bromine is less reactive than wet bromine; however, dry bromine reacts vigorously with aluminium, titanium, mercury as well as alkaline earth and alkaline metals.

Applications

Elemental bromine is used to manufacture a wide variety of bromine compounds used in industry and agriculture. Traditionally the largest use of bromine was in the production of 1, 2-Dibromoethane which in turn was used as a gasoline anti-knock agent for leaded gasolines before they were largely phased out due to environmental considerations.Bromine is also used in making fumigants, flameproofing agents, water purification

compounds, dyes, medicinals, sanitizes, inorganic bromides for photography, etc.Bromine is used to make brominated vegetable oil, which is used as an emulsifier in

many citrus-flavored soft drinks.

History

Bromine (Gr. bromos for stench) was discovered by Antoine Balard at salt marshes of Montpellier in 1826 but was not produced in quantity until 1860.

Occurrence

Bromine occurs in nature as bromide salts in very diffuse amounts in crustal rock. Due to leaching bromide salts have accumulated in sea water (85 ppm), and may be economically recovered from brine wells and the Dead Sea (up to 5000 ppm). Approx-imately 500 million kilograms ($350 million USD) of bromine are produced per year (2001) worldwide with the United States and Israel being the primary producers.



Previous Page

Krypton

Krypton is a chemical element in the periodic table that has the symbol Kr, atomic number 36 and atomic weight of 83.798. It is a Noble gas.

• Name: Krypton• Symbol: Kr• Atomic number: 36• Atomic weight: 83.798• Standard state: gas at 298 K• CAS Registry ID: 7439-90-9• Group in periodic table: 18• Group name: Noble gas• Period in periodic table: 4• Block in periodic table: p-block• Colour: colourless• Classification: Non-metallic

A colorless noble gas, krypton occurs in trace amounts in the atmosphere, is isolated by fractionating liquefied air, and is often used with other rare gases in fluorescent lamps. Krypton is inert for most practical purposes but it is known to form com-pounds with fluorine. Krypton can also form clathrates with water when atoms of it are trapped in a lattice of the water molecules.


Krypton, a so-called noble gas due to its very low chemical reactivity, is characterized by a brilliant green and orange spectral signature. It is one of the products of uranium fission. Solidified krypton is white and crystalline with a face-centered cubic crystal structure which is a common property of all "rare gases."

Applications

The SI standard definition of the length of the meter was, from 1960 to 1983, based on the light emitted by excited krypton atoms: specifically, the meter was defined as 1,650,763.73 wavelengths of the orange-red emission line emitted by krypton-86 at-oms.Krypton clathrates have been made with hydroquinone and phenol. Kr-85 is used in

chemical analysis. When it is placed in various solids kryptonates are formed and their activity is sensitive to surface chemical reactions. This noble gas is also used in pho-tographic flash lamps needed for high-speed photography but this use is limited be-cause of the high cost of krypton.

History

Krypton (Greek kryptos meaning "hidden") was discovered in 1898 by William Ramsay and Morris Travers in residue left from evaporating nearly all components of liquid air. In 1960 an international agreement defined the meter in terms of light emitted from a krypton isotope. This agreement replaced the longstanding standard meter located in Paris which was a metal bar made of a platinum-iridium alloy (the bar was originally estimated to be one ten millionth of a quadrant of the earth's polar cir-cumference. In October 1983 the krypton standard was in turn replaced by the Bu-reau International des Poids et Mesures (International Bureau of Weights and Mea-sures). A meter is now defined as the distance that light travels in a vacuum during 1/299,792,458 s.

Occurrence

The concentration of this gas in earth's atmosphere is about 1 ppm. It can be extract-ed from liquid air by fractional distillation.

Compounds

Like the other rare gases krypton is widely considered to be chemically inert. How-ever, studies conducted since the 1960s have uncovered some compounds of krypton. Krypton difluoride has been made in gram quantities and can be produced in several different ways. Other fluorides and a salt of a krypton called oxyacid have also been found. ArKr+ and KrH+ molecule-ions have been investigated and there is evidence for KrXe or KrXe+.

Isotopes

Naturally occurring krypton is composed of six stable isotopes. Krypton's spectral signature is easily produced with some very sharp lines. Kr-81 is the product of atmo-spheric reactions with the other naturally occurring isotopes of krypton. It is radioac-tive with a half-life of 250,000 years. Like xenon, krypton is highly volatile when it is near surface waters and Kr-81 has therefore been used for dating old (50,000 - 800,000 year) groundwater. Kr-85 is an inert radioactive noble gas with a half-life of 10.76 years, that is produced by fission of uranium and plutonium. Sources have included nuclear bomb testing, nuclear reactors, and the release of Kr-85 during the reprocess-ing of fuel rods from nuclear reactors. A strong gradient exists between the northern and southern hemispheres where concentrations at the North Pole are approximately 30% higher than the South Pole due to convective mixing.


Previous Page

From Wikipedia, the free encyclopedia and webelements Rubidium

Rubidium is a chemical element in the periodic table that has the symbol Rb, atomic number 37 and atomic weight of 85.4678. It is a Alkali metal.

• Name: Rubidium• Symbol: Rb• Atomic number: 37• Atomic weight: 85.4678• Standard state: solid at 298 K• CAS Registry ID: 7440-17-7• Group in periodic table: 1• Group name: Alkali metal• Period in periodic table: 5• Block in periodic table: s-block• Colour: silvery white• Classification: Metallic

Rubidium is a soft, silvery-white metallic element of the alkali metal group. Rb-87, a naturally occurring isotope, is (slightly) radioactive. Rubidium is highly reactive, with properties similar to other elements in group 1, like igniting spontaneously in air.


Rubidium is the second most electropositive of the alkaline elements and can be a liq-uid at room temperature. Like other group 1 elements this metal ignites spontaneous-ly in air and reacts violently in water, liberating and sometimes igniting hydrogen. Also like other alkali metals, it forms amalgams with mercury and it can form alloys with gold, caesium, sodium, and potassium. The element gives a yellowish violet color to a flame.

Applications

Rubidium can be easily ionized, and because of this has been considered for use in ion engines for space vehicles (but caesium and xenon are more efficient for this pur-pose).Other potential or current uses:


Previous Page

* As a working fluid in vapor turbines. * As a getter in vacuum tubes. * As a photocell component. * In the making of special glasses. * RbAg4I5 has the highest room temperature conductivity of any known ionic crys-

tal. This property could be useful in thin film batteries and in other applications. * Also considered for use in a thermoelectric generator using the magnetohydro-

dynamic principle where rubidium ions are formed by heat at high temperature and passed through a magnetic field. These conduct electricity and act like an armature of a generator thereby generating an electric current. * Rubidium compounds are sometimes used in fireworks to give them a purple color.

History

Rubidium (L rubidus, deepest red) was discovered in 1861 by Robert Bunsen and Gus-tav Kirchhoff in the mineral lepidolite through the use of a spectroscope. However this element had minimal industrial use until the 1920s. Historically, the most import-ant use for rubidium has been in research and development, primarily in chemical and electronic applications.

Occurrence

This element is considered to be the 16th most abundant element in the earth's crust. It occurs naturally in the minerals leucite, pollucite, and zinnwaldite, which contains traces of up to 1% of its oxide. Lepidolite contains 1.5% rubidium and this is the com-mercial source of the element. Some potassium minerals and potassium chlorides also contain the element in commercially significant amounts.One notable source is also in the extensive deposits of pollucite at Bernic Lake, Man-

itoba. Rubidium metal can be produced by reducing rubidium chloride with calcium among other methods. Rubidium forms at least four oxides: Rb2O, Rb2O2, Rb2O3, RbO2. In 1997 the cost of this metal in small quantities was about US$ 25/gram.

Isotopes

There are 24 isotopes of rubidium known with naturally occurring rubidium being composed of just two isotopes; Rb-85 (72.2%) and the radioactive Rb-87 (27.8%). Normal mixes of rubidium are radioactive enough to expose photographic film in approxim-etely 30 to 60 days. Rb-87 has a half-life of 48.8 x 109 years. It readily substitutes for potassium in minerals, and is therefore fairly widespread. Rb has been used extensive-ly in dating rocks; Rb-87 decays to stable strontium-87 by emission of a negative beta particle.During fractional crystallization, Sr tends to become concentrated in plagioclase,

leaving Rb in the liquid phase. Hence, the Rb/Sr ratio in residual magma may increase over time, resulting in rocks with increasing Rb/Sr ratios with increasing differenti-ation. Highest ratios (10 or higher) occur in pegmatites. If the initial amount of Sr is known or can be extrapolated, the age can be determined by measurement of the Rb and Sr concentrations and the Sr-87/Sr-86 ratio. The dates indicate the true age of the minerals only if the rocks have not been subsequently altered. See Rubidium-Stron-

tium dating for a more detailed discussion.



Previous Page

Strontium

Strontium is a chemical element in the periodic table that has the symbol Sr, the atomic number 38 and atomic weight of 87.62. It is a Alkaline Earth Metal.

• Name: Strontium• Symbol: Sr• Atomic number: 38• Atomic weight: 87.62• Standard state: solid at 298 K• CAS Registry ID: 7440-24-6• Group in periodic table: 2• Group name: Alkaline earth metal• Period in periodic table: 5• Block in periodic table: s-block• Colour: silvery white• Classification: Metallic

An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. This metal turns yellow when exposed to air and occurs in celestite and strontianite. Sr-90 is present in radioactive fallout and has a half-life of 28 years.


Due to its extreme reactivity to air, this element always naturally occurs combined with other elements and compounds, as in the minerals strontianite, celestite, etc. It is isolated as a yellowish metal and is somewhat malleable. It is chiefly employed (as in the nitrate) to color pyrotechnic flames red.Strontium is a bright silvery metal that is softer than calcium and even more reactive

in water; strontium will decompose on contact to produce strontium hydroxide and hydrogen gas. It burns in air to produce both a strontium oxide and strontium nitride, but since it does not react with nitrogen below 380°C it will only form the oxide spon-taneously at room temperature. It should be kept under kerosene to prevent oxida-tion; freshly exposed strontium metal rapidly turns a yellowish color with the forma-tion of the oxide. Finely powdered strontium metal will ignite spontaneously in air. Volatile strontium salts impart a beautiful crimson color to flames, and these salts are used in pyrotechnics and in the production of flares. Natural strontium is a mixture of four stable isotopes.

Applications

At present the primary use for strontium is in glass for color television cathode ray tubes.

Also: * It is also used in producing ferrite magnets and in refining zinc. * Strontium titanate has an extremely high refractive index and an optical disper-

sion greater than that of diamond, making it useful in a variety of interesting optics applications. * Strontium titanate has been used as a gemstone, but is very soft and so scratches

easily so it is not common in this role. It does not occur naturally. * Strontium is also used in fireworks to provide a red color upon burning.

History

Adair Crawford recognized the mineral strontianite, named after the Scottish town of Strontian, as differing from other barium minerals in 1790. However, Klaproth and Hope discovered strontium itself in 1798 and metallic strontium was first isolated by Sir Humphry Davy in 1808 using electrolysis.

Occurrence

Strontium commonly occurs in nature, averaging 0.034% of all igneous rock and is found chiefly as the form of the sulfate mineral celestite (SrSO4) and the carbonate strontianite (SrCO3). Of the two, celestite occurs much more frequently in sedimen-tary deposits of sufficient size to make development of mining facilities attractive. Strontianite would be the more useful of the two common minerals because stron-tium is used most often in the carbonate form, but few deposits have been discovered that are suitable for development. The metal can be prepared by electrolysis of the melted chloride mixed with potassium chloride, or is made by reducing strontium oxide with aluminium in a vacuum at a temperature at which strontium distills off. Three allotropes of the metal exist, with transition points at 235 and 540°C. Strontium metal (98% pure) in January 1990 cost about $5/oz. The largest commercially exploited deposits are found in England. Strontium can be isolated from strontium chloride.

Isotopes

The alkali earth metal strontium has four stable, naturally occurring isotopes: Sr-84 (0.56%), Sr-86 (9.86%), Sr-81 (7.0%) and Sr-88 (82.58%). Only Sr-87 is radiogenic; it is pro-duced by decay from the radioactive alkali metal rubidium-87, which has a half-life of 48,800,000 years. Thus, there are two sources of Sr-87 in any material: that formed during primordial nucleo-synthesis along with Sr-84, Sr-86 and Sr-88, as well as that formed by radioactive decay of Rb-87. The ratio Sr-87/Sr-86 is the parameter typically reported in geologic investigations. Because strontium has an atomic radius similar to that of calcium, it readily substitutes for Ca in minerals. Sr-87/Sr-86 ratios in minerals and rocks have values ranging from about 0.7 to greater than 4.0.


Previous Page

Sixteen unstable isotopes are known to exist. Of greatest importance is Sr-90 with a half-life of 29 years. It is a by-product of nuclear fallout and presents a health prob-lem since it substitutes for calcium in bone, preventing expulsion from the body. This isotope is one of the best long-lived high-energy beta emitters known, and is used in SNAP (Systems for Nuclear Auxiliary Power) devices. These devices hold promise for use in spacecraft, remote weather stations, navigational buoys, etc, where a light-weight, long-lived, nuclear-electric power source is required.


Yttrium

Yttrium is a chemical element in the periodic table that has the symbol Y, atomic number 39 and atomic weight of 88.90585. It is a Transition metal.

• Name: Yttrium• Symbol: Y• Atomic number: 39• Atomic weight: 88.90585• Standard state: solid at 298 K• CAS Registry ID: 7440-65-5• Group in periodic table: 3• Group name: (none)• Period in periodic table: 5• Block in periodic table: d-block• Colour: silvery white• Classification: Metallic

A silvery metallic transition metal, yttrium is common in rare-earth minerals and two of its compounds are used to make the red color in color televisions.


Yttrium is a silver-metallic, lustrous rare earth metal that is relatively stable in air and chemically resembles the lanthanides. Shavings or turnings of the metal can ig-nite in air when they exceed 400°C. When yttrium is finely divided it is very unstable in air. The metal has a low cross section for nuclear capture. The common oxidation state of yttrium is +3.

Applications

Yttrium oxide is the most important yttrium compound and is widely used to make YVO4 europium and Y2O3 europium phosphors that give the red color in color televi-sion picture tubes.

Other uses; * Yttrium oxide is also used to make yttrium-iron-garnets which are very effective

microwave filters.


Previous Page

* Yttrium iron, aluminium, and gadolinium garnets (e.g. Y3 Fe5 O12 and Y3 Al5 O12) have interesting magnetic properties. Yttrium iron garnet is very efficient as an acoustic energy transmitter and transducer. Yttrium aluminium garnet has a hardness of 8.5 and is also used as a gemstone (simulated diamond). * Small amounts of the element (0.1 to 0.2%) have been used to reduce grain size

of chromium, molybdenum, titanium, and zirconium. It is also used to increase the strength of aluminium and magnesium alloys. * Used as a catalyst for ethylene polymerization. * Yttrium aluminium garnet, yttrium lithium fluoride, and yttrium vanadate are

used in combination with dopants such as neodymium or erbium in infrared lasers. * This metal can be used to deoxidize vanadium and other nonferrous metals. Yttrium has been studied for possible use as a nodulizer in the making of nodular cast

iron which has increased ductility (the graphite forms compact nodules instead of flakes to form nodular cast iron). Potentially, yttrium can be used in ceramic and glass formulas, since yttrium oxide has a high melting point and imparts shock resistance and low expansion characteristics to glass.

History

Yttrium (Ytterby, a Swedish village near Vaxholm) was discovered by Johan Gadolin in 1794 and isolated by Friedrich Wohler in 1828 as an impure extract of yttria through the reduction of yttrium anhydrous chloride (YCl3) with potassium. Yttria (Y2O3) is the oxide of yttrium and was discovered by Johan Gadolin in 1794 in a gadolinite mineral from Ytterby.In 1843 Carl Mosander was able to show that yttira could be divided into the oxides

(or earths) of three different elements. "Yttria" was the name used for the most basic one and the others were named erbia and terbia.A quarry is located near the village of Ytterby that yielded many unusual minerals

that contained rare earths and other elements. The elements erbium, terbium, and ytterbium and yttrium have all been named after this same town.

Occurrence

This element is found in almost all rare earth minerals and in uranium ores but is never found in nature as a free element. Yttrium is commercially recovered from monazite sand (3% content, (Ce, La, etc.)PO4) and from bastnasite (0.2% content, (Ce, La, etc.)(CO3)F. It is commercially produced by reducing yttrium fluoride with calcium metal but it can also be produced using other techniques.It is difficult to separate from other rare earths and when extracted, is a dark gray

powder. Lunar rock samples from the Apollo program have a relatively high yttrium content.

Isotopes

Natural yttrium is composed of only one isotope (Y-89). The most stable radioisotopes are Y-88 which has a half life of 106.65 days and Y-91 with a half life of 58.51 days. All the other isotopes have half lifes of less than a day except Y-87 which has a half life of

79.8 hours.The dominant decay mode below the stable Y-89 is electron capture and the domi-

nant mode after it is beta emission. Twenty six unstable isotopes have been character-ized. Y-90 exists in equilibrium with its parent isotope strontium-90, which is a prod-uct of nuclear explosions.



Previous Page

Zirconium

Zirconium is a chemical element in the periodic table that has the symbol Zr, atomic number 40 and atomic weight of 91.224. It is a Transition Metal.

• Name: Zirconium• Symbol: Zr• Atomic number: 40• Atomic weight: 91.224• Standard state: solid at 298 K• CAS Registry ID: 7440-67-7• Group in periodic table: 4• Group name: (none)• Period in periodic table: 5• Block in periodic table: d-block• Colour: silvery white• Classification: Metallic

A lustrous gray-white, strong transition metal that resembles titanium, zirconium is obtained chiefly from zircon and is very corrosion resistant. Zirconium is primarily used in nuclear reactors for a neutron absorber and to make corrosion-resistant al-loys.


It is a grayish-white metal, lustrous and exceptionally corrosion resistant. Zirconium is lighter than steel and its hardness is similar to copper. When it is finely divided, the metal can spontaneously ignite in air, especially at high temperatures (it is much more difficult to ignite the solid metal). Zirconium zinc alloy becomes magnetic at tempera-tures below 35°K. Common oxidation states of zirconium include +2, +3 and +4.

Applications

The major end uses of zircon (ZrSiO4) are refractories, foundry sands (including in-vestment casting), and ceramic opacification. Zircon is also marketed as a natural gemstone used in jewelry, and its oxide is processed to produce the diamond simu-lant, cubic zirconia.Other uses;

* Zirconium has a low absorption cross section for neutrons, which makes it ideal for nuclear energy uses, such as cladding fuel elements. More than 90% of zirconium met-al production is consumed by commercial nuclear power generation. Modern com-mercial scale reactors can use as much as a 150,000 meters of zirconium alloy tubing. * Extensively used by the chemical industry for piping in corrosive environments. * Zirconium is pyrophoric (flammable) and has been used in military incendiaries. * Its carbonate is used in poison ivy lotions. * Impure zirconium oxide, zirconia, is used to make laboratory crucibles that can

withstand heat shock, for linings of metallurgical furnaces, and by the ceramic and glass industries as a refractory material. * Human tissues can easily tolerate this metal which makes it suitable for some arti-

ficial joints and limbs. * Also used in heat exchangers, as a "getter" in vacuum tubes, in lamp filaments and

various specialty alloys. When alloyed with niobium, zirconium becomes supercon-ductive at low temperatures and is used to make superconductive magnets with pos-sible large-scale electrical power uses.

History

Zirconium (Arabic zarkûn from Persian zargûn meaning "gold like") was discovered in 1789 by Martin Heinrich Klaproth and isolated in 1824 by Jons Jakob Berzelius.The zirconium containing mineral zircon, or its variations (jargon, hyacinth, jacinth,

or ligure), were mentioned in biblical writings. The mineral was not known to contain a new element until Klaproth analyzed a jargon from Ceylon in the Indian Ocean. He named the new element Zirkonertz (zirconia). The impure metal was isolated first by Berzelius by heating a mixture of potassium and potassium zirconium fluoride in a small decomposition process conducted in an iron tube. Pure zirconium wasn't pre-pared until 1914.

Occurrence

Zirconium is never found in nature as a free metal. The principal economic source of zirconium is the zirconium silicate mineral, zircon (ZrSiO4) which is found in depos-its located in Australia, Brazil, India, Russia, and the United States (it is extracted as a dark sooty powder, or as a gray metallic crystalline substance). Zirconium and hafni-um are contained in zircon at a ratio of about 50 to 1 and are difficult to separate.Zircon is a coproduct or byproduct of the mining and processing of heavy-mineral

sands for the titanium minerals, ilmenite and rutile, or tin minerals. Zirconium is also in 30 other recognized mineral species including baddeleyite. This metal is commer-cially produced by reduction of the chloride with magnesium in the Kroll Process, and through other methods. Commercial-quality zirconium still has a content of 1 to 3% hafnium.This element is also abundant in S-type stars, and has been detected in the sun and

meteorites. Lunar rock samples brought back from several Apollo program missions to the moon have a very high zirconium oxide content relative to terrestrial rocks.

Isotopes


Previous Page

Naturally occurring zirconium is composed of four stable isotopes and one extreme-ly long-lived radioisotope (Zr-96). The second most stable radioisotope is Zr-93 which has a half life of 1.53 million years. Eighteen other radioisotopes have been character-ized. Most of these have half lives that are less than a day except Zr-95 (64.02 days), Zr-88 (63.4 days), and Zr-89 (78.41 hours). The primary decay mode is electron capture before Zr-92 and the primary mode after is beta decay.


Niobium

Niobium (or columbium) is a chemical element in the periodic table that has the sym-bol Nb, atomic number 41 and atomic weight of 92.90638. It Is a Transition metal.

• Name: Niobium• Symbol: Nb• Atomic number: 41• Atomic weight: 92.90638• Standard state: solid at 298 K• CAS Registry ID: 7440-03-1• Group in periodic table: 5• Group name: (none)• Period in periodic table: 5• Block in periodic table: d-block• Colour: grey metallic• Classification: Metallic

A rare, soft, gray, ductile transition metal, niobium is found in niobite and used in al-loys. The most notable alloys are used to make special steels and strong welded joints. Niobium was discovered in a variety of columbite (now called niobite) and was at first named after this mineral.


Niobium is a shiny grey, ductile metal that takes on a bluish tinge when exposed to air at room temperature for extended periods. Niobium's chemical properties are al-most identical to the chemical properties of tantalum, which appears below niobium in the periodic table.When it is processed at even moderate temperatures niobium must be placed in a

protective atmosphere. The metal begins to oxidize in air at 200°C and its oxidation states are +2, +3, +5.

Applications

Niobium has a number of uses: it is a component of some stainless steels and an al-loy of other nonferrous metals. These alloys are strong and are often used in pipeline construction.


Previous Page

Other uses:* The metal has a low capture cross-section for thermal neutrons and so finds use in

the nuclear industries. * It is also the metal used in arc welding rods for some stabilized grades of stainless

steel. * Because of its bluish color, niobium is also used in body piercing jewelry (usually as

an alloy). * Appreciable amounts of niobium in the form of high-purity ferroniobium and nick-

el niobium are used in nickel-, cobalt-, and iron-base superalloys for such applications as jet engine components, rocket subassemblies, and heat-resisting and combustion equipment. For example, advanced air frame systems such as those used in the Gemini program used this metal. * Niobium is being evaluated as an alternative to tantalum in capacitors.Niobium becomes a superconductor when lowered to cryogenic temperatures. At at-

mospheric pressure, it has the highest critical temperature of the elemental supercon-ductors, 9.3 K. In addition, it is one of the three elemental superconductors that are Type II (the others being vanadium and technetium), meaning it remains a supercon-ductor when subjected to high magnetic fields. Niobium-tin and niobium-titanium al-loys are used as wires for superconducting magnets capable of producing exceedingly strong magnetic fields.

History

Niobium (Greek mythology: Niobe, daughter of Tantalus) was discovered by Charles Hatchett in 1801. Hatchett found niobium in columbite ore that was sent to England in the 1750s by John Winthrop who was the first governor of Connecticut. There was a considerable amount of confusion about the difference between the closely-relat-ed niobium and tantalum that wasn't resolved until 1846 by Heinrich Rose and Jean Charles Galissard de Marignac who rediscovered the element. Since Rose was unaware of Hatchett's work he gave the element a different name, niobium. In 1864 Christian Blomstrand was the first to prepare the metal. He did this by reducing niobium chlo-ride by heating it in a hydrogen atmosphere.Columbium was the name originally given to this element by Hatchet but the Inter-

national Union of Pure and Applied Chemistry (IUPAC) officially adopted "niobium" as the name for element 41 in 1950 after 100 years of controversy. Many leading chemi-cal societies and government organizations refer to it by the official IUPAC name but most leading metallurgists, metal societies, and most leading American commercial producers still refer to the metal by the original "columbium."

Occurrence

The element is never found as a free element but does occur in niobite (Fe, Mn)(Nb, Ta)2O6, niobite-tantalite [(Fe, Mn)(Ta, Nb)2O6], pyrochlore (NaCaNb2O6F), and euxenite [(Y, Ca, Ce, U, Th)(Nb, Ta, Ti)2O6]. Minerals that contain niobium often also contain tantalum. Large deposits of niobium have been found associated with carbonatites (carbon-silicate rocks) and as a constituent of pyrochlore. Brazil and Canada are the major producers of niobium mineral concentrates and extensive ore reserves are also in Nigeria, Democratic Republic of Congo, and in Russia.

Isotopes

Naturally occurring niobium is composed of one stable isotope (Nb-93). The most sta-ble radioisotopes are Nb-92 with a half life of 34.7 million years, Nb-94 (half life: 20300 years), and Nb-91 with a half life of 680 years. There is also a meta state at 0.031 mega electron volts whose half life is 16.13 years. Twenty three other radioisotopes have been characterized. Most of these have half lives that are less than two hours except Nb-95 (35 days), Nb-96 (23.4 hours) and Nb-90 (14.6 hours). The primary decay mode be-fore the stable Nb-93 is electron capture and the primary mode after is beta emission with some neutron emission occurring in the first mode of the two mode decay of Nb-104, 109 and 110.



Previous Page

Molybdenum

Molybdenum is a chemical element in the periodic table that has the symbol Mo, atomic number 42 and atomic weight of 95.94. It is a Transition metal.

• Name: Molybdenum• Symbol: Mo• Atomic number: 42• Atomic weight: 95.94• Standard state: solid at 298 K• CAS Registry ID: 7439-98-7• Group in periodic table: 6• Group name: (none)• Period in periodic table: 5• Block in periodic table: d-block• Colour: grey metallic• Classification: Metallic


Molybdenum is a transition metal. The pure metal is silvery white in color and very hard, and has one of the highest melting points of all pure elements. In small quanti-ties, molybdenum is effective at hardening steel. Molybdenum is important in plant nutrition, and is found in certain enzymes, including xanthine oxidase.

Applications

Over 2/3 of all molybdenum is used in alloys. Molybdenum use soared during World War I, when demand for tungsten made tungsten scarce, and high strength steels were at a premium.Molybdenum is used to this day in high strength alloys, and high temperature steels.

Special molybdenum containing alloys, such as the Hastelloys ®, are notably heat re-sistant and corrosion resistant.Molybdenum is used in aircraft and missile parts, and in filaments. Molybdenum

finds use as a catalyst in the petroleum industry, especially in catalysts for removing organic sulfurs from petroleum products. Mo-99 is used in the nuclear isotope indus-try. Molybdenum oranges are pigments, ranging from red-yellow to a bright red or-ange, used in paints, inks, plastics, and rubber compounds. Molybdenum disulphide is

a good lubricant, especially at high temperatures. Molybdenum is also used in some electronic applications, as the conductive metal layers in thin-film transistors (TFTs).

History

Molybdenum (from the Greek molybdos meaning "lead-like") is not found free in nature, and the compounds that can be found were, until the late 18th century, con-fused with compounds of other elements, such as carbon or lead. In 1778 Carl Wilhelm Scheele was able to determine that molybdenum was separate from graphite and lead, and was able to isolate the oxide of the metal from molybdenite. In 1782 Hjelm was able to isolate an impure extract of the metal by reducing the oxide with carbon.Molybdenum was little used and remained in the laboratory until the late 19th centu-

ry. Then a French company, Schneider and Co, tried molybdenum as an alloying agent in armor plate and noted its useful properties.

Occurrence

Though molybdenum is found in such minerals as wulfenite (MoO4Pb) or powellite (CaMnO4), the main commercial source of molybdenum is molybdenite (MoS2). Mo-lybdenum is mined directly, and is also recovered as a byproduct of copper mining. Molybdenum is present in ores from 0.01% to about 0.5%. About half of the world's molybdenum is mined in the United States, with Phelps Dodge Corporation being a primary provider.The Russian Luna 24 mission discovered a single grain of pure Molybdenum in a py-

roxene fragment taken from Mare Crisium on the Moon.

Biological Role

There is a trace requirement for molybdenum in plants, and soils can be barren due to molybdenum deficiencies. Plants and animals generally have molybdenum, pres-ent in amounts of a few parts per million. In plants, molybdenum is involved in the pathways of nitrogen fixation and nitrate reduction, and in animals, molybdenum is involved in the pathways of purine degradation and formation of uric acid. In some animals, adding a small amount of dietary molybdenum enhances growth.

Isotopes

Molybdenum has six stable isotopes and almost two dozen radioisotopes, the vast majority of which have half lives measured in seconds. Mo-99 is used in sorpation generators that are used to create Tc-99 for the nuclear isotope industry. The market for Mo-99 products is estimated to be on the order of $100 million US dollars a year.


Previous Page

From Wikipedia, the free encyclopedia and webelements Technetium

Technetium ( Gr. technetos meaning artificial ) is a chemical element in the periodic table that has the symbol Tc, atomic number 43 and atomic weight of 98. It is a Transi-tion metal.

• Name: Technetium• Symbol: Tc• Atomic number: 43• Atomic weight: 98• Standard state: solid at 298 K• CAS Registry ID: 7440-26-8• Group in periodic table: 7• Group name: (none)• Period in periodic table: 5• Block in periodic table: d-block• Colour: silvery grey metallic• Classification: Metallic

A silvery gray, radioactive, crystalline transition metal that is very rarely found in na-ture, technetium occurs as one of the fission products of uranium and is used in bone imaging and corrosion protection. Chemical properties of this element are intermedi-ate between rhenium and manganese.


Technetium is a silvery-gray metal that slowly tarnishes in moist air. Under oxidizing conditions technetium (VII) will exist as the pertechnetate ion, TcO4-. The chemistry of technetium is intermediate between rhenium and manganese. Technetium dis-solves in aqua regia, nitric acid, and concentrated sulfuric acid, but it is not soluble in hydrochloric acid. This element is a very good corrosion inhibitor for steel and the metal is an excellent superconductor at temperatures below 11 K.This element is unusual because it has no stable isotopes and is therefore extremely

rare on earth. Common oxidation states of technetium include +2, +4, +5, +6 and +7.

Applications

Technetium is one of the most powerful known preventatives of rust, and is also a


Previous Page

valuable source of beta rays. Ammonium pertechnate (NH4TcO4), is a specialized cor-rosion preventer for steel. Five parts per million of KTcO4 in aerated distilled water protects mild carbon steel at temperatures up to 250°C. This protection is limited to closed systems due to the radioactive nature of technetium.

Other uses; * Tc-95m ("m" stands for meta state) with a half-life of 61 days is used in radioactive

tracer studies. * Tc-99m (half-life 6.01 hours) is used in many radioactive isotope medical tests due

to its short half-life, the gamma ray energy it emits, and its ability to chemically bind to many active biomolecules. * Organic technetium compounds are used in bone imaging. * Technetium is an excellent superconductor at tempuratures of 11 kelvins and be-

low. * Technetium is commercially available to holders of O.R.N.L. permits at a price of

$60/g.

History

Technetium (Greek technetos meaning "artificial") was discovered by Carlo Perrier and Emilio Segrè in Italy in 1937. The researchers found it in a sample of molybdenum sent to them by Ernest Lawrence. The sample was bombarded by deuterium nuclei in the University of California, Berkeley cyclotron which gave them the isotope Tc-97. Technetium was the first element to be artificially produced.For a number of years there was a gap in the periodic table at element 43. Dmitri

Mendeleev predicted that this missing element would be chemically similar to manga-nese and gave it the name ekamanganese. In 1925 Walter Noddack and Ida Tacke, the discoverers of rhenium, reported the discovery of element 43 and named it masurium, but their report was never confirmed and thus generally accepted as mistaken. (Some chemists have challenged this view.) The development of nuclear energy in the mid 20th century generated the first known samples of element 43 by nuclear reactions.

Occurrence

Once it was available in macroscopic quantities i.e. enough to determine its chemical and physical properties, it was discovered to exist naturally elsewhere in the universe. Some red giant stars (S-, M-, and N-types) contain an emission line in their spectrum corresponding to the presence of technetium. Its presence in red giants has led to the establishment of new theories about the production of heavy elements in stars.Since its discovery, there have been many searches in terrestrial materials for natural

sources. In 1962, technetium-99 was isolated and identified in pitchblende from Africa in very small quantities as a spontaneous fission product of uranium-238. This discov-ery was made by B.T. Kenna and P.K. Kuroda.Tc-99 is produced as a byproduct from the fission of uranium in nuclear reactors and

it is prepared by chemically separating it from reactor waste.

Isotopes

Technetium is one of two elements in the first 83 that have no stable isotopes (the other element is promethium). The most stable radioisotopes are Tc-98 with a half-life of 4.2 million years, Tc-97 (half-life: 2.6 million years) and Tc-99 (half-life: 211,100 years). Twenty-two other radioisotopes have been characterized with atomic weights rang-ing from 87.933 amu (Tc-88) to 112.931 amu (Tc-113). Most of these have half-lives that are less than an hour except Tc-93 (2.75 hours), Tc-94 (293 minutes), Tc-95 (20 hours), and Tc-96 (4.28 days). There are also numerous meta states with Tc-97m being the most stable with a half-life of 90.1 days (0.097 MeV). This is followed by Tc-95m (half life: 61 days, 0.038 MeV), and Tc-99m (half-life: 6.01 hours, 0.143 MeV).The primary decay mode before the most stable isotope, Tc-98, is electron capture

and the primary mode after is beta emission with one instance of election capture during the first mode of the two mode decay of Tc-100. The primary decay product before Tc-98 is molybdenum and the primary product after is ruthenium (the product of the first decay mode of Tc-100 is Mo, however).



Previous Page

Ruthenium

Ruthenium is a chemical element in the periodic table that has the symbol Ru, atomic number 44 and atomic weight of 101.07. It is a transition metal Precious metal element.

• Name: Ruthenium• Symbol: Ru• Atomic number: 44• Atomic weight: 101.07• Standard state: solid at 298 K• CAS Registry ID: 7440-18-8• Group in periodic table: 8• Group name: Precious metal or Platinum group metal• Period in periodic table: 5• Block in periodic table: d-block• Colour: silvery white metallic• Classification: Metallic

A rare transition metal of the platinum group, ruthenium is found associated with platinum ores and used as a catalyst in some platinum alloys.


A polyvalent hard white metal, ruthenium is a member of the platinum group, has four crystal modifications and does not tarnish at normal temperatures, but does oxidize explosively. Ruthenium dissolves in fused alkalis, is not attacked by acids but is attacked by halogens at high temperatures and by hydroxides. Small amounts of ruthenium can increase the hardness of platinum and palladium. The corrosion resis-tance of titanium is increased markedly by the addition of a small amount of rutheni-um.This metal can be plated either through electrodeposition or by thermal decomposi-

tion methods. One ruthenium-molybdenum alloy has been found to be superconduc-tive at 10.6 K. The oxidation states of ruthenium range from +1 to +8, and -2 is known, though oxidation states of +2, +3, and +4 are most common.

Applications

Due to its highly effective ability to harden platinum and palladium, ruthenium is

used in Pt and Pd alloys to make severe wear resistance electrical contacts. * 0.1% ruthenium is added to titanium to improve its corrosion resistance a hundredfold. Ruthenium is also a versatile catalyst: Hydrogen sulfide can be split by light by using an aqueous suspension of CdS particles loaded with ruthenium dioxide. This may be useful in the removal of H2S from oil refineries and from other industrial processes.Organometallic ruthenium carbene and allenylidene complexes have recently been

found as highly efficient catalysts for olefin metathesis (= redistribution of olefinic =CRR' groups) with important applications in organic and pharmaceutical chemistry.Recently, large metallo-organic complexes of ruthenium have been found to exhibit

anti-tumor activity and the first of a new group of anti-cancer medicine are now in the stage of clinical trials. Some ruthenium complexes absorb light throughout the visible spectrum and are being actively researched in various, potential, solar energy technologies.

History

Ruthenium (Latin Ruthenia meaning "Russia") was discovered and isolated by Karl Klaus in 1844. Klaus showed that ruthenium oxide contained a new metal and obtained 6 grams of ruthenium from the part of crude platinum that is insoluble in aqua regia.Jöns Berzelius and Gottfried Osann nearly discovered ruthenium in 1827. The men

examined residues that were left after dissolving crude platinum from the Ural Moun-tains in aqua regia. Berzelius did not find any unusual metals, but Osann thought he found three new metals and named one of them ruthenium.It is also possible that Polish chemist Jedrzej Sniadecki isolated element 44 (which he

called vestium) from platinum ores in 1807. However his work was never confirmed and he later withdrew his discovery claim.

Occurrence

This element is generally found in ores with the other platinum group metals in the Ural Mountains and in North and South America. Small but commercially important quantities are also found in pentlandite extracted from Sudbury, Ontario and in py-roxinite deposits in South Africa.This metal is commercially isolated through a complex chemical process in which hy-

drogen is used to reduce ammonium ruthenium chloride yielding a powder. The pow-der is then consolidated by powder metallurgy techniques or by argon-arc welding.

Compounds

Ruthenium compounds are often similar in properties to those of cadmium and ex-hibit at least eight oxidation states, but +2, +3, and +4 states are the most common.

Isotopes

Naturally occurring ruthenium is composed of seven isotopes. The most stable radio-isotopes are Ru-106 with a half-life of 373.59 days, Ru-103 with a half-life of 39.26 days and Ru-97 with a half-life of 2.9 days.Fifteen other radioisotopes have been characterized with atomic weights ranging


Previous Page

from 89.93 amu (Ru-90) to 114.928 (Ru-115). Most of these have half-lifes that are less than five minutes except Ru-95 (half-life: 1.643 hours) and Ru-105 (half-life: 4.44 h).The primary decay mode before the most abundant isotope, Ru-102, is electron cap-

ture and the primary mode after is beta emission. The primary decay product before Ru-102 is technetium and the primary mode after is rhodium.


Rhodium

Rhodium is a chemical element in the periodic table that has the symbol Rh, atomic number 45 and atomic weight of 102.90550. It is a transition metal Precious metal ele-ment..

• Name: Rhodium• Symbol: Rh• Atomic number: 45• Atomic weight: 102.90550• Standard state: solid at 298 K• CAS Registry ID: 7440-16-6• Group in periodic table: 9• Group name: Precious metal or Platinum group metal• Period in periodic table: 5• Block in periodic table: d-block• Colour: silvery white metallic• Classification: Metallic

A rare silvery-white hard transition metal, rhodium is a member of the platinum group, is found in platinum ores and is used in alloys with platinum and as a catalyst.


Rhodium is a hard silvery white and durable metal that has a high reflectance. It changes in air to the resquioxide while slowly cooling from a red hot state but at high-er temperatures converts back to the metal. Rhodium has both a higher melting point and lower density than platinum. It is not attacked by acids and only dissolves in aqua regia.

Applications

The primary use of this element is as an alloying agent for hardening platinum and palladium. These alloys are used in furnace windings, bushings for glass fiber produc-tion, thermocouple elements, electrodes for aircraft spark plugs, and laboratory cru-cibles.

Other uses:


Previous Page

* It is used as an electrical contact material due to its low electrical resistance, low and stable contact resistance, and its high corrosion resistance. * Plated rhodium, made by electroplating or evaporation, is extremely hard and is

used for optical instruments. * This metal finds use in jewelry and for decorations. * It is also a highly useful catalyst in a number of industrial processes (notably it is

used in the catalytic system of automobile catalytic converters and for catalytic car-bonylation of methanol to produce acetic acid).

History

Rhodium (Greek rhodon meaning "rose") was discovered in 1803 by William Hyde Wollaston soon after his discovery of palladium. Wollaston made this discovery in En-gland using crude platinum ore that he presumably obtained from South America.His procedure involved dissolving the ore in aqua regia, neutralizing the acid with

sodium hydroxide (NaOH). He then precipitated the platinum metal by adding am-monium chloride, NH4Cl, as ammonium chloroplatinate. The element palladium was removed as palladium cyanide after treating the solution with mercuric cyanide. The material that remained was a red substance with rhodium chloride salts and rhodium metal was isolated via reduction with hydrogen gas.

Occurrence

The industrial extraction of rhodium is complex as the metal occurs in ores mixed with other metals such as palladium, silver, platinum, and gold. It is found in platinum ores and obtained free as a white inert metal which it is very difficult to fuse.Principal sources of this element are located in river sands of the Ural Mountains,

in North and South America and also in the copper-nickel sulfide mining area of the Sudbury, Ontario region. Although the quantity at Sudbury is very small, the large amount of nickel ore processed makes rhodium recovery cost effective. However, the annual world production of this element is only 7 or 8 tons and there are very few rhodium minerals.

Isotopes

Naturally occurring rhodium is composed of only one isotope (Rh-103). The most stable radioisotopes are Rh-101 with a half-life of 3.3 years, Rh-102 with a half-life of 207 days, and Rh-99 with a half-life of 16.1 days. Twenty other radioisotopes have been characterized with atomic weights ranging from 92.926 u (Rh-93) to 116.925 u (Rh-117). Most of these have half-lifes that are less than an hour except Rh-100 (half-life: 20.8 hours) and Rh-105 (half-life: 35.36 hours). There are also numerous meta states with the most stable being Rhm-102 (0.141 MeV) with a half-life of about 2.9 years and Rhm-101 (0.157 MeV) with a half-life of 4.34 days.The primary decay mode before the only stable isotope, Rh-103, is electron capture

and the primary mode after is beta emission. The primary decay product before Rh-103 is ruthenium and the primary product after is palladium.



Previous Page

Palladium

Palladium is a chemical element with symbol Pd, atomic number 46 and atomic weight of 106.42 It is a transition metal Precious metal element.

• Name: Palladium• Symbol: Pd• Atomic number: 46• Atomic weight: 106.42• Standard state: solid at 298 K• CAS Registry ID: 7440-05-3• Group in periodic table: 10• Group name: Precious metal or Platinum group metal• Period in periodic table: 5• Block in periodic table: d-block• Colour: silvery white metallic• Classification: Metallic

A rare silver-white transition metal of the platinum group, palladium resembles plat-inum chemically and is extracted from some copper and nickel ores. It is primarily used as an industrial catalyst and in jewelry.


Palladium is a soft steel-white metal that resembles platinum, does not tarnish in air, and is the least dense and has the lowest melting point of the platinum group metals. It is soft and ductile when annealed and greatly increases its strength and hardness when it is cold-worked. Palladium is chemically attacked by sulfuric and nitric acid but dissolves slowly in hydrochloric acid. This metal also does not react with oxygen at normal temperatures.This metal has the uncommon ability to absorb up to 900 times its own volume of hy-

drogen at room temperatures. It is thought that this possibly forms palladium hydride - Pd2H - but it is not yet clear if this is a true chemical compound.Common oxidation states of palladium are +2, +3 and +4. Recently, palladium com-

pounds in which palladium has oxidation state +6 were synthesized.

Applications

When it is finely divided, palladium forms a good catalyst and is used to speed up hydrogenation and dehydrogenation reactions, as well as in petroleum cracking. It is also alloyed and used in jewelry.

Other uses:* White gold is an alloy of gold that is decolorized by the addition of palladium. * Similar to gold, palladium can be beaten into a thin leaf form as thin as 1/250,000

in. * Hydrogen easily diffuses through heated palladium; thus, it provides a means of

purifying the gas. * Telecommunications switching-system equipment uses palladium. * Palladium is also used in dentistry, watchmaking, in aircraft spark plugs and in the

production of surgical instruments and electrical contacts.

History

Palladium was discovered by William Hyde Wollaston in 1803. This element was named by Wollaston in 1804 after the asteroid Pallas, which was discovered two years earlier.Wollaston found element 46 in crude platinum ore from South America. He did this

by dissolving the ore in aqua regia, neutralizing the solution with sodium hydroxide, NaOH, precipitating platinum as ammonium chloroplatinate through treatment with ammonium chloride, NH4Cl, and then adding mercuric cyanide to form the compound palladium cyanide. Finally, he heated the resulting compound in order to extract pal-ladium metal.The compound palladium chloride was at one time prescribed as a tuberculosis treat-

ment at the rate of 0.065 g per day (approximately 1 mg per kg of body weight). This treatment did not have too many ill side effects but was later replaced by more effec-tive drugs. The element played an essential role in the Fleischmann-Pons experiment, also known as cold fusion.

Occurrence

Palladium is found as a free metal and alloyed with platinum and gold with platinum group metals in placer deposits of the Ural Mountains, Australia, Ethiopia, South and North America. However it is commercially produced from nickel-copper deposits found in South Africa and Ontario (the huge volume of ore processed makes this ex-traction profitable in spite of its low concentration in these ores).

Isotopes

Naturally-occurring palladium is composed of six isotopes. The most stable radioiso-topes are Pd-107 with a half-life of 6.5 million years, Pd-103 with a half-life of 17 days, and Pd-100 with a half-life of 3.63 days. Eighteen other radioisotopes have been char-acterized with atomic weights ranging from 92.936 u (Pd-93) to 119.924 u (Pd-120). Most of these have half-lifes that are less than a half an hour except Pd-101 (half-life: 8.47 hours), Pd-109 (half-life: 13.7 hours), and Pd-112 (half-life: 21 hours).The primary decay mode before the most abundant stable isotope, Pd-106, is electron


Previous Page

capture and the primary mode after is beta decay. The primary decay product before Pd-106 is rhodium and the primary product after is silver.Radiogenic Ag-107 is a decay product of Pd-107 and was first discovered in the Santa

Clara, California meteorite of 1978. The discoverers suggest that the coalescence and differentiation of iron-cored small planets may have occurred 10 million years after a nucleosynthetic event. Pd-107 versus Ag correlations observed in bodies, which have clearly been melted since accretion of the solar system, must reflect the presence of short-lived nuclides in the early solar system.


Silver

Silver is a chemical element in the periodic table that has the symbol Ag, (L. Argen-tum) atomic number 47 and atomic weight of 107.8682. It is a transition metal Precious metal element.

• Name: Silver• Symbol: Ag• Atomic number: 47• Atomic weight: 107.8682• Standard state: solid at 298 K• CAS Registry ID: 7440-22-4• Group in periodic table: 11• Group name: Coinage metal• Period in periodic table: 5• Block in periodic table: d-block• Colour: silver• Classification: Metallic

A soft white lustrous transition metal, silver has the highest electrical and thermal conductivity of any metal and occurs in minerals and in free form. This metal is used in coins, jewelry, tableware and photography.


Silver is a very ductile and malleable (slightly harder than gold) univalent coinage metal with a brilliant white metallic luster that can take a high degree of polish. It has the highest electrical conductivity of all metals, even higher than copper, but its greater cost has prevented it from being widely used in place of copper for electrical purposes.Pure silver also has the highest thermal conductivity, whitest color, the highest opti-

cal reflectivity (although it is a poor reflector of ultraviolet), and the lowest contact resistance of any metal. Silver halides are photosensitive and are remarkable for the effect of light upon them. This metal is stable in pure air and water, but does tarnish when it is exposed to ozone, hydrogen sulfide, or air with sulfur in it. The most com-mon oxidation states of silver are +1 and +2.

Applications


Previous Page

The principal use of silver is as a precious metal and its halide salts, especially silver nitrate, are also widely used in photography (which is the largest single end use of silver).

Some other uses for silver are as follows: * Electrical and electronic products, which need silver's superior conductivity, even

when tarnished. For example, printed circuits are made using silver paints, and com-puter keyboards use silver electrical contacts. * Mirrors which need silver's superior reflectivity for visible light are made with sil-

ver as the reflecting material. Common mirrors are backed with aluminium. * Silver has been coined to produce money since 700 BC by the Lydians, in the form

of electrum. Later, silver was refined and coined in its pure form. The words for "sil-ver" and "money" are the same in at least 14 languages. * The metal is chosen for its beauty in the manufacture of jewelry and silverware,

which are traditionally made from the silver alloy known as Sterling silver, which is 92.5% silver. * The malleability, non-toxicity and beauty of silver make it useful in dental alloys

for fittings and fillings. * Silver's catalytic properties make it ideal for use as a catalyst in oxidation reac-

tions; for example, the production of formaldehyde from methanol and air by means of silver screens or crystallites containing a minimum 99.95 weight-percent silver. * Used to make solder and brazing alloys, electrical contacts, and high capacity sil-

ver-zinc and silver-cadmium batteries. * Silver sulfide, also known as Silver Whiskers, is formed when silver electrical con-

tacts are used in an atmosphere rich in hydrogen sulfide. * Silver fulminate is a powerful explosive. * Silver chloride can be made transparent and is used as a cement for glass. * Silver iodide has been used in attempts to seed clouds to produce rain. * In legend, silver is traditionally seen as harmful to supernatural creatures like

werewolves and vampires. The use of silver fashioned into bullets for firearms is a popular application. * Silver oxide is used as a positive electrode(cathode) in watch batteries.

History

Silver (Anglo-Saxon, Seolfor siolfur; Ag is from the Latin argentum) has been known since ancient times. It is mentioned in the book of Genesis and slag heaps found in Asia Minor and on the islands of the Aegean Sea indicate that silver was being sepa-rated from lead as early as the 4th millennium BC. Silver has been used for thousands of years as ornaments and utensils, for trade, and as the basis for many monetary sys-tems. It was long considered the second most precious metal, second only to gold.Associated with the moon, as well as with the sea and various lunar goddesses, the

metal was referred to by alchemists by the name luna.One of the alchemical symbols for silver is a crescent moon with the open part on the

left.The metal mercury was thought of as a kind of silver, though the two elements are

chemically unrelated; its names hydrargyrum ("watery silver") and the English quick-silver attest to this.

In heraldry, the argent, in addition to being shown as silver (this has been shown at times with real silver in official representations), can also been shown as white. Occa-sionally, the word "silver" is used rather than argent; sometimes this is done across-the-board, sometimes to avoid repetition of the word "argent" in blazon. Europeans found huge amount of silver in the New World in Zacatecas, Mexico and PotosÃ , which triggered a period of inflation in Europe.The Rio de la Plata was named after silver (in Spanish, plata), and in turn lent the

meaning of its name to Argentina.

Occurrence

Silver is found in native form, combined with sulfur, arsenic, antimony, or chlorine and in various ores such as argentite (Ag2S) and horn silver (AgCl). The principal sources of silver are copper, copper-nickel, gold, lead and lead-zinc ores obtained from Canada, Mexico, Peru, Australia and the United States.This metal is also produced during the electrolytic refining of copper. Commercial

grade fine silver is at least 99.9% pure silver and purities greater than 99.999% are available. Mexico is the largest silver producer. According to the Secretary of Econom-ics of Mexico, it produced 2747 tons in 2000, about 15% of the annual production of the world.

IsotopesNaturally occurring silver is composed of the two stable isotopes Ag-107 and Ag-109

with Ag-107 being the most abundant (51.839% natural abundance). Twenty-eight ra-dioisotopes have been characterized with the most stable being Ag-105 with a half-life of 41.29 days, Ag-111 with a half-life of 7.45 days, and Ag-112 with a half-life of 3.13 hours. All of the remaining radioactive isotopes have half-lifes that are less than an hour and the majority of these have half lifes that are less than 3 minutes. This element also has numerous meta states with the most stable being Agm-128 (t* 418 years), Agm-110 (t* 249.79 days) and Agm-107 (t* 8.28 days).Isotopes of silver range in atomic weight from 93.943 amu (Ag-94) to 123.929 amu

(Ag-124). The primary decay mode before the most abundant stable isotope, Ag-107, is electron capture and the primary mode after is beta decay. The primary decay prod-ucts before Ag-107 are palladium (element 46) isotopes and the primary products after are cadmium (element 48) isotopes.The palladium isotope Pd-107 decays by beta emission to Ag-107 with a half-life of 6.5

million years. Iron meteorites are the only objects with a high enough Pd/Ag ratio to yield measurable variations in Ag-107 abundance. Radiogenic Ag-107 was first discov-ered in the Santa Clara meteorite in 1978. The discoverers suggest that the coalescence and differentiation of iron-cored small planets may have occurred 10 million years after a nucleosynthetic event. Pd-107 versus Ag correlations observed in bodies, which have clearly been melted since the accretion of the solar system, must reflect the presence of live short-lived nuclides in the early solar system.


Previous Page

From Wikipedia, the free encyclopedia and webelementsCadmiumCadmium is a chemical element in the periodic table that has the symbol Cd, atomic

number 48 and atomic weight 112.411. It is a Metallic element.

• Name: Cadmium• Symbol: Cd• Atomic number: 48• Atomic weight: 112.411• Standard state: solid at 298 K• CAS Registry ID: 7440-43-9• Group in periodic table: 12• Group name: (none)• Period in periodic table: 5• Block in periodic table: d-block• Colour: silvery grey metallic• Classification: Metallic

A relatively rare, soft, bluish-white, toxic transition metal, cadmium occurs with zinc ores and is used largely in batteries.Notable characteristicsCadmium is a soft, malleable, ductile, bluish-white bivalent metal which can be easily

cut with a knife. It is similar in many respects to zinc but lends itself to more complex compounds. The most common oxidation state of cadmium is +2, though rare exam-ples of +1 can be found.

ApplicationsAbout three-fourths of cadmium is used in batteries (especially Ni-Cd batteries) and

most of the remaining one-fourth is used mainly for pigments, coatings and plating, and as stabilizers for plastics. Other uses; Used in some of the lowest melting alloys. Due to a low coefficient of friction and very good fatigue resistance, it is used in bear-ing alloys. 6% of cadmium finds use in electroplating. Many kinds of solder contain this metal. As a barrier to control nuclear fission. Compounds containing cadmium are used in black and white television phosphors and also in the blue and green phos-phors for color television picture tubes.Cadmium forms various salts, with cadmium sulfide being the most common. This

sulfide is used as a yellow pigment. Used in some semiconductors Some cadmium compounds are employed in PVC as stabilizers. Used in the first neutrino dector. Used in batteries, namely Nickel Cadmium. (NiCd).


Previous Page

HistoryCadmium (Latin cadmia, Greek kadmeia meaning "calamine") was discovered in Ger-

many in 1817 by Friedrich Strohmeyer. Strohmeyer found the new element within an impurity in zinc carbonate (calamine) and for 100 years Germany remained the only important producer of the metal. The metal was named after the Latin word for cala-mine since the metal was found in this zinc compound. Strohmeyer noted that some impure samples of calamine changed color when heated but pure calamine did not.Even though cadmium and its compounds are highly toxic, the British Pharmaceuti-

cal Codex from 1907 states that cadmium iodide was used as a medicine to treat "en-larged joints, scrofulous glands, and chilblains". In 1927, the International Conference on Weights and Measures redefined the meter in terms of a red cadmium spectral line (1m = 1,553,164.13 wavelengths). This definition has since been changed (see krypton).

OccurrenceCadmium-containing ores are rare and when found they occur in small quantities.

Greenockite (CdS), the only cadmium mineral of importance, is nearly always associ-ated with sphalerite (ZnS). Consequently, cadmium is produced mainly as a byproduct from mining, smelting, and refining sulfide ores of zinc, and to a lesser degree, lead and copper. Small amounts of cadmium, about 10% of consumption, are produced from secondary sources, mainly from dust generated by recycling iron and steel scrap. Production in the United States began in 1907 but it was not until after World War I that cadmium came into wide use.

IsotopesNaturally occurring cadmium is composed of 6 stable isotopes. 27 radioisotopes have

been characterized with the most stable being Cd-113 with a half-life of 7.7 quadrillion years, Cd-109 with a half-life of 462.6 days, and Cd-115 with a half-life of 53.46 hours. All of the remaining radioactive isotopes have half-lifes that are less than 2.5 hours and the majority of these have half lifes that are less than 5 minutes. This element also has 8 meta states with the most stable being Cdm-113 (t1/2 14.1 years), Cdm-115 (t1/2 44.6 days) and Cdm-117 (t1/2 3.36 hours).The isotopes of cadmium range in atomic weight from 96.935 amu (Cd-97) to 129.934

amu (Cd-138). The primary decay mode before the second most abundant stable-iso-tope, Cd-112, is electron capture and the primary mode after is beta emission. The pri-mary decay product before Cd-112 is element 47 (silver) and the primary product after is element 49 (indium)


Indium

Indium is a chemical element in the periodic table that has the symbol In, atomic number 49 and atomic weight of 114.818. It is a Metallic element.

• Name: Indium• Symbol: In• Atomic number: 49• Atomic weight: 114.818• Standard state: solid at 298 K• CAS Registry ID: 7440-74-6• Group in periodic table: 13• Group name: (none)• Period in periodic table: 5• Block in periodic table: p-block• Colour: silvery lustrous grey• Classification: Metallic

This rare, soft, malleable and easily fusible poor metal, is chemically similar to alu-minium or gallium but looks more like zinc (zinc ores are also the primary source of this metal). Its current primary application is to form thin-films for use as lubricated layers (during World War II it was widely used to coat bearings in high-performance aircraft).


Indium is a very soft, silvery-white true metal that has a bright luster. As a pure metal indium emits a high-pitched "cry" when it is bent. Both gallium and indium are able to wet glass.

Applications

The first large-scale application for indium was as a coating for bearings in high-per-formance aircraft engines during World War II. Afterwards, production gradually increased as new uses were found in fusible alloys, solders, and electronics. In the middle and late 1980s, the development of indium phosphide semiconductors and indium-tin-oxide thin films for liquid crystal displays (LCD) aroused much interest. By 1992, the thin-film application had become the largest end use.


Previous Page

Other uses: * Used in the manufacture of low-melting alloys. An alloy consisting of 24% indium

and 76% gallium is liquid at room temperature. * Used to make photoconductors, germanium transistors, rectifiers, and thermis-

tors. * Can also be plated onto metals and evaporated onto glass which forms a mirror

which is as good as those made with silver but has higher corrosion resistance. * Its oxide is used in the making of electroluminescent panels.

History

Indium (named after the indigo line in its atomic spectrum) was discovered by Ferdi-nand Reich and Theodor Richter in 1863 while they were testing zinc ores with a spec-trograph in search of thallium. Richter went on to isolate the metal in 1867.

Occurrence

Indium is produced mainly from residues generated during zinc ore processing but is also found in iron, lead, and copper ores. The amount of indium consumed is largely a function of worldwide LCD production. Increased manufacturing efficiency and recy-cling (especially in Japan) maintain a balance between demand and supply. The aver-age indium price for 2000 was US$188 per kilogram.Up until 1924, there was only about a gram of isolated indium on the planet. The Earth

is estimated to contain about 0.1 ppm of indium which means it is about as abundant as silver. Canada is a leading producer of indium, producing more than 1,000,000 troy ounces (31,100 kg) in 1997.


Tin

Tin is a chemical element in the periodic table that has the symbol Sn (L. Stannum), atomic number 50 and atomic weight of 118.710. It is a Metallic element.

• Name: Tin• Symbol: Sn• Atomic number: 50• Atomic weight: 118.710• Standard state: solid at 298 K• CAS Registry ID: 7440-31-5• Group in periodic table: 14• Group name: (none)• Period in periodic table: 5• Block in periodic table: p-block• Colour: silvery lustrous grey• Classification: Metallic

This silvery, malleable poor metal that is not easily oxidized in air and resists corro-sion is found in many alloys and is used to coat other metals to prevent corrosion. Tin is obtained chiefly from the mineral cassiterite where it occurs as an oxide.


Tin is a malleable, ductile, highly crystalline, silvery-white metal whose crystal struc-ture causes a "tin cry" when a bar of tin is bent (caused by crystals breaking). This metal resists corrosion from distilled sea and soft tap water, but can be attacked by strong acids, alkalis, and by acid salts. Tin acts as a catalyst when oxygen is in solution and helps accelerate chemical attack.Tin forms Sn2 is when it is heated in the presence of air. Sn2, in turn, is feebly acidic

and forms stannate (tin) salts with basic oxides. Tin can be highly polished and is used as a protective coat for other metals in order to prevent corrosion or other chemical action. This metal combines directly with chlorine and oxygen and displaces hydro-gen from dilute acids. Tin is malleable at ordinary temperatures but is brittle when it is heated.

Allotropes


Previous Page

Solid tin has two allotropes at normal pressure. At low temperatures it exists as gray or alpha tin, which has a cubic crystal structure similar to silicon and germanium. When warmed above that 13.2°C it changes into white or beta tin, which is metallic and has a tetragonal structure. It slowly changes back to the gray form when cooled, which is called the tin pest or tin disease. However, this transformation is affected by impurities such as aluminium and zinc and can be prevented from occurring through the addition of antimony or bismuth.

Applications

Tin bonds readily to iron, and has been used for coating lead or zinc and steel to pre-vent corrosion. Tin-plated steel containers are widely used for food preservation, and this forms a large part of the market for metallic tin. British English calls them "tins"; Americans call them "cans". One thus-derived use of the slang term "tinnie" or "tinny" means "can of beer".

Other uses: * Some important tin alloys are: bronze, bell metal, Babbitt metal, die casting alloy,

pewter, phosphor bronze, soft solder, and White metal. * The most important salt formed is tin chloride, which has found use as a reducing

agent and as a mordant in the calico printing process. Electrically conductive coatings are produced when tin salts are sprayed onto glass. These coatings have been used in panel lighting and in the production of frost-free windshields. * Window glass is most often made via floating molten glass on top of molten tin

(float glass) in order to make a flat surface (this is called the Pilkington process). * Tin is also used in solders for joining pipes or electrical/electronic circuits, in bear-

ing alloys, in glass-making, and in a wide range of tin chemical applications. * Tin foil is a common wrapping material for foods and drugs; hence one use of the

slang term "tinnie" or "tinny" for a small retail package of a drug such as cannabis.Tin becomes a superconductor below 3.72 K. In fact, tin was one of the first supercon-

ductors to be studied; the Meissner effect, one of the characteristic features of su-perconductors, was first discovered in superconducting tin crystals. The niobium-tin compound Nb3Sn is commercially used as wires for superconducting magnets, due to the material's high critical temperature (18K) and critical magnetic field (25 T). A su-perconducting magnet weighing only a couple of kilograms is capable of producing magnetic fields comparable to a conventional electromagnet weighing tons.

History

Tin (anglo-Saxon, tin, Latin stannum) is one of the earliest metals known and was used as a component of bronze from antiquity. Because of its hardening effect on copper, tin was used in bronze implements as early as 3,500 BC. Tin mining is believed to have started in Cornwall and Devon ( esp Dartmoor) in Classical times, and a thriv-ing tin trade developed with the civilizations of the Mediterranean. However the pure metal was not used until about 600 BC.In modern times, the word "tin" is often (improperly) used as a generic phrase for

any silvery metal that comes in thin sheets. Most everyday objects that are common-ly called tin, such as aluminium foil, beverage cans, and tin cans, are actually made of steel or aluminium, although tin cans do contain a small coating of tin to inhibit rust.

Likewise, so-called "tin toys" are usually made of steel, and may or may not have a small coating of tin to inhibit rust.

Occurrence

About 35 countries mine tin throughout the world. Nearly every continent has an im-portant tin-mining country. Tin is produced by reducing the ore with coal in a rever-beratory furnace. This metal is a relatively scarce element with an abundance in the earth's crust of about 2 ppm, compared with 94 ppm for zinc, 63 ppm for copper, and 12 ppm for lead.IsotopesTin is the element with the greatest number of stable isotopes (ten). 18 additional un-

stable isotopes are known.



Previous Page

AntimonyAntimony is a chemical element in the periodic table that has the symbol Sb, (L. Stib-

ium) atomic number 51 and atomic weight of 121.760. It is a Semi-metallic element. In the Pnictogen group.

• Name: Antimony• Symbol: Sb• Atomic number: 51• Atomic weight: 121.760• Standard state: solid at 298 K• CAS Registry ID: 7440-36-0• Group in periodic table: 15• Group name: Pnictogen• Period in periodic table: 5• Block in periodic table: p-block• Colour: silvery lustrous grey• Classification: Semi-metallic

A metalloid, antimony has four allotropic forms. The stable form of antimony is a blue-white metal. Yellow and black antimony are unstable non-metals. Used in flame-proofing, paints, ceramics, enamels, a wide variety of alloys, and rubber.

Notable CharacteristicsAntimony in its elemental form is a silvery white, brittle, fusible, crystalline solid

that exhibits poor electrical and heat conductivity properties and vaporizes at low temperatures. A metalloid, antimony, resembles metal in its appearance and physical properties, but does not chemically react as a metal. It is also attacked by oxidizing acids and halogens. Antimony and some of its alloys expand on cooling.Estimates of the abundance of antimony in the Earth's crust range from 0.2 to 0.5

ppm. Antimony is chalcophile, occurring with sulfur and the heavy metals lead, cop-per, and silver.

ApplicationsAntimony is increasingly being used in the semiconductor industry in the produc-

tion of diodes, infrared detectors, and Hall-effect devices. As an alloy, this semi-metal greatly increases lead's hardness and mechanical strength. The most important use of antimony metal is as a hardener in lead for storage batteries.

Other uses:

* Batteries* Antifriction alloys* Type metal* Small arms and tracer bullets* Cable sheathing* MatchesAntimony compounds in the form of oxides, sulfides, sodium antimonate, and an-

timony trichloride are used in the making of flame-proofing compounds, ceramic enamels, glass, paints, and pottery. Antimony trioxide is the most important of the antimony compounds and is primarily used in flame-retardant formulations. These flame-retardant applications include such markets as children's clothing, toys, air-craft and automobile seat covers. Also, antimony sulfide is one of the ingredients to the modern match.

HistoryAntimony was recognized in antiquity (3000 BC or earlier) in various compounds,

and it was prized for its fine casting qualities. It was first reported scientifically by Tholden in 1450, and was known to be a metal by the beginning of the 17th century. The origin of the name "antimony" is not clear; the term may come from the Greek words "anti" and "monos", which approximately means "opposed to solitude" as it was thought never to exist in its pure form, or from the Arabian expression "Antos Am-mon", which could be translated as "bloom of the god Ammon".The natural sulfide of antimony, stibnite, was known and used in Biblical times as

medicine and as a cosmetic. The relationship between antimony's modern name and its symbol is complex; the Coptic name for the cosmetic powder antimony sulfide was borrowed by the Greeks, which was in turn borrowed by Latin, resulting in stibium. The chemical pioneer Jacob Berzelius used an abbreviation of this name for antimo-ny in his writings, and his usage became the standard symbol. Antimony was until recently used for the treatment of schistosomiasis. Antimony attaches itself to sulfur atoms in certain enzymes which are used both by the parasite and human host. Small doses can kill the parasite without causing damage to the patient.

SourcesEven though this element is not abundant, it is found in over 100 mineral species.

Antimony is sometimes found native, but more frequently it is found in the sulfide stibnite (Sb2S3) which is the predominant ore mineral. Commercial forms of antimony are generally ingots, broken pieces, granules, and cast cake. Other forms are powder, shot, and single crystals.



Previous Page

TelluriumTellurium is a chemical element in the periodic table that has the symbol Te, atomic

number 52 and atomic weight of 127.60. It is a Semi-metallic element.in the Chalcogen group.

• Name: Tellurium• Symbol: Te• Atomic number: 52• Atomic weight: 127.60• Standard state: solid at 298 K• CAS Registry ID: 13494-80-9• Group in periodic table: 16• Group name: Chalcogen• Period in periodic table: 5• Block in periodic table: p-block• Colour: silvery lustrous grey• Classification: Semi-metallic

A brittle silver-white metalloid which looks like tin, tellurium is chemically related to selenium and sulfur. This element is primarily used in alloys and as a semiconductor.

Notable CharacteristicsTellurium is a relatively rare element, in the same chemical family as oxygen, sulfur,

selenium, and polonium (the chalcogens). When crystalline, tellurium is silvery-white and when it is in its pure state it has a metallic luster. This is a brittle and easily pul-verized metalloid. Amorphous tellurium is found by precipitating it from a solution of tellurous or telluric acid. However, there is some debate whether this form is really amorphous or made of minute crystals.Tellurium is a p-type semiconductor that shows a greater conductivity in certain di-

rections which depends on atomic alignment.Chemically related to selenium and sulfur, the conductivity of this element increases

slightly when exposed to light. It can be doped with copper, gold, silver, tin, or other metals. Tellurium has a greenish-blue flame when burned in normal air and forms tel-lurium dioxide as a result. When in its molten state, tellurium is corrosive to copper, iron, and stainless steel.

Applications

It is mostly used in alloys with other metals. It is added to lead to improve its strength, durability and to decreases the corrosive action of sulfuric acid. When add-ed to stainless steel and copper it makes these metals more workable.

Other uses: * It is alloyed into cast iron for chill control. * Used in ceramics. * Bismuth telluride has found use in thermoelectric devices.Tellurium is also used in blasting caps, and has potential applications in cadmium

telluride solar panels. Some of the highest efficiencies for solar cell electric power generation have been obtained by using this material, but this application has not yet caused demand to increase significantly.

HistoryTellurium (Latin tellus meaning "earth") was discovered in 1782 by Franz Joseph Muller

von Reichstein in Romania. In 1798 it was named by Martin Heinrich Klaproth who ear-lier isolated it.The 1960s brought growth in thermoelectric applications for tellurium, as well as its

use in free-machining steel, which became the dominant use.

OccurrenceTellurium is sometimes found in its native form, but is more often found as the tel-

luride of gold (calaverite), and combined with other metals. The principal source of tellurium is from anode muds produced during the electrolytic refining of blister copper. Commercial-grade tellurium, which is not toxic, is usually marketed as minus 200-mesh powder but is also available as slabs, ingots, sticks, or lumps. The yearend price for tellurium in 2000 was US$ 14 per pound.

CompoundsTellurium is in the same series as sulfur and selenium and forms similar compounds.

A compound with metal or hydrogen and similar ions is called a telluride. Gold and silver tellurides are considered good ore.IsotopesThere are 30 known isotopes of tellurium with atomic masses that range from 108

to 137. Naturally found tellurium consists of eight isotopes (listed in the table to the right).



Previous Page

Iodine

Iodine (from the Gr. Iodes, meaning "violet"), is a chemical element in the period-ic table that has the symbol I, atomic number 53 and atomic weight 126.90447. It is a Non-metallic Halogen element.

• Name: Iodine• Symbol: I• Atomic number: 53• Atomic weight: 126.90447• Standard state: solid at 298 K• CAS Registry ID: 7553-56-2• Group in periodic table: 17• Group name: Halogen• Period in periodic table: 5• Block in periodic table: p-block• Colour: violet-dark grey, lustrous• Classification: Non-metallic

This is an insoluble element that is required as a trace element for living organisms. Chemically, iodine is the least reactive of the halogens, and the most electropositive metallic halogen. Iodine is primarily used in medicine, photography and in dyes.


Iodine is a bluish-black, lustrous solid that sublimes at standard temperatures into a blue-violet gas that has an irritating odor. This halogen also forms compounds with many elements, but is less active than the other member of its series and has some metallic-like properties. Iodine dissolves easily in chloroform, carbon tetrachloride, or carbon disulfide to form purple solutions (It is only slightly soluble in water). The deep blue color with starch solution is characteristic of the free element.ApplicationsIn areas where there is little iodine in the diet - typically remote inland areas where

no marine foods are eaten - iodine deficiency gives rise to goitre, so called endemic goitre. In many (but not all) such areas, this is now prevented by the addition of small amounts of iodine to table salt in form of sodium iodide, potassium iodide, potassium iodate - this product is known as iodised salt.

Other uses:* One of the halogens, it is an essential trace element; the thyroid hormones, thyrox-

ine and triiodotyronine contain iodine. * Tincture of iodine (3% elemental iodine in water/ethanol base) is an essential com-

ponent of any emergency survival kit, used both to disinfect wounds and to sanitize surface water for drinking (3 drops/L, let stand for 30 minutes) * Iodine compounds are important in the field of organic chemistry and are very

useful in medicine. * Iodides and thyroxine which contains iodine, are both used in internal medicine

and, in combination with alcohol (as tincture of iodine) are used externally to disin-fect wounds * Potassium iodide is used in photography * Tungsten iodide is used to stabilise the filaments in light bulbs. * Nitrogen triiodide is an explosive, too unstable to be used commercially, but is

commonly used in college pranks. * Iodine-131 is used as a tracer in medicine * Potassium iodide (KI) tablets can be given to people in a nuclear disaster area. KI

prevents the body from absorbing the radioactive iodine produced at the disaster area.

History

Iodine (Gr. iodes meaning violet) was discovered by Barnard Courtois in 1811. He was the son of a manufacturer of Saltpeter (potassium nitrate, a vital part of gunpowder). At the time France was at war and gunpowder was in great demand. Saltpeter was isolated from seaweed washed up on the coasts of Normandy and Brittany. To isolate the potassium nitrate, seaweed was burned and the ash then washed with water. The remaining waste was destroyed by adding hydrochloric acid. One day Curtois added too much sulfuric acid and cloud of purple vapor rose. Curtois noted that the vapor crystallised on cold surfaces making dark crystals. Curtois suspected that this was a new element but lacked the money to pursue his observations.However he gave samples to his friends, Charles Bernard Desormes (1777 - 1862) and

Nicolas Clément (1779 - 1841) to continue research. He also gave some of the substance to Joseph Louis Gay-Lussac (1778 - 1850), a well-known chemist at that time, and to André-Marie Ampêre (1775-1836). On November 29, 1813 Dersormes and Clément made public, Curtois's discovery. They described the substance to a meeting of the Imperial Institute of France. On December 6 Gay-Lussac announced that the new substance was either an element or a compound of oxygen. Ampêre had given some of his sample to Humphrey Davy (1778 - 1829). Davy did some experiments on the substance and noted its similarity to chlorine. Davy sent a letter dated December 10 to the Royal Society of London stating that he had identified a new element. A large argument erupted be-tween Davy and Gay-Lussac over who identified iodine first but both scientists ac-knowledged Bernard Curtois as the first to isolate the element.

Occurrence

Iodine can be prepared in an ultrapure form through the reaction of potassium io-dide with copper (II) sulfate. There are also several other methods of isolating this element.


Previous Page

Isotopes

There are thirty isotopes of iodine and only one, I-127, is stable. The artificial radio-isotope I-131 (a beta emitter) which has a half-life of 8 days, has been used in treating cancer and other pathologies of the thyroid glands. The most common compounds of iodine are the iodides of sodium and potassium (KI) and the iodates (KIO3). I-129 (half-life 15.7 million years) is a product of Xe-129 spallation in the atmosphere, but is also the result of uranium and plutonium fission. I-129 was used in rainwater studies following the Chernobyl accident. It also has been used as a ground-water tracer and as an indicator of waste dispersion into the natural environment. Other applications may be hampered by the production of I-129 in the lithosphere through a number of decay mechanisms.In many ways, I-129 is similar to Cl-36. It is a soluble halogen, fairly non-reactive, ex-

ists mainly as a non-sorbing anion, and is produced by cosmogenic, thermonuclear, and in-situ reactions. In hydrologic studies, I-129 concentrations are usually report-ed as the ratio of I-129 to total I (which is virtually all I-127). As is the case with Cl-36/Cl, I-129/I ratios in nature are quite small, 10-14 to 10-10 (peak thermonuclear I-129/I during the 1960s and 1970s reached about 10-7). I-129 differs from Cl-36 in that its half-life is longer (1.6 vs 0.3 million years), it is highly biophilic, and occurs in multiple ionic forms (commonly, I - and iodate) which have different chemical behaviors.


Xenon

Xenon is a chemical element in the periodic table that has the symbol Xe, atomic number 54 and atomic weight of 131.293. It is a Noble gas.

• Name: Xenon• Symbol: Xe• Atomic number: 54• Atomic weight: 131.293• Standard state: gas at 298 K• CAS Registry ID: 7440-63-3• Group in periodic table: 18• Group name: Noble gas• Period in periodic table: 5• Block in periodic table: p-block• Colour: colourless• Classification: Non-metallic

A colorless, very heavy, odorless noble gas, xenon occurs in the earth's atmosphere in trace amounts and was part of the first noble gas compound synthesized.


Xenon is a member of the zero-valence elements that are called noble or inert gases. The word "inert" is no longer used to describe this chemical series since some zero valence elements do form compounds. In a gas filled tube, xenon emits a blue glow when the gas is excited by electrical discharge. Using several hundred kilobars of pressure, metallic xenon has been made. Xenon can also form clathrates with water when atoms of it are trapped in a lattice of the water molecules.

Applications

This gas is most widely and most famously used in light-emitting devices called Xe-non flash lamps, which are used in photographic flashes, stroboscopic lamps, to excite the active medium in lasers which then generate coherent light, in bactericidal lamps (rarely), and in certain dermatological uses. Continuous, short-arc, high pressure Xe-non arc lamps have a color temperature closely approximating noon sunlight and are used in solar simulators, some projection systems, and other specialized uses. They


Previous Page

are an excellent source of short wave ultaviolet light and they have intense emissions in the near infrared, which are used in some night vision systems.

Other uses:* Used as a general anaesthetic. * In nuclear energy applications it is used in bubble chambers, probes, and in other

areas where a high molecular weight is a desirable quality. * Its perxenates are used as oxidizing agents in analytical chemistry. * The isotope Xe-133 is useful as a radioisotope. * Hyperpolarized MRI of the lungs and other tissues using 129Xe.

History

Xenon (Greek xenon meaning "stranger") was discovered in England by William Ram-say and Morris Travers in 1898 in the residue left over from evaporating components of liquid air.OccurrenceIt is a trace gas in Earth's atmosphere, occurring in one part in twenty million. The el-

ement is obtained commercially through extraction from the residues of liquefied air. This noble gas is naturally found in gases emitted from some mineral springs. Xe-133 and Xe-135 are synthesized by neutron irradiation within air-cooled nuclear reactors.

Compounds

Before 1962, xenon and the other noble gases were generally considered to be chemi-cally inert and not able to form compounds. Evidence since this time has been mount-ing that xenon, along with other noble gases, do in fact form compounds. Some of the xenon compounds are xenon difluoride, tetrafluoride, hexafluoride, hydrate, and deuterate, as well as sodium perxenate.The highly explosive compound xenon trioxide has also been made. There are at least

80 xenon compounds in which fluorine or oxygen is bonded to xenon. Some com-pounds of xenon are colored but most are colorless.

Isotopes

Naturally occurring xenon is made of eight stable and one slightly radioactive iso-topes. Beyond these stable forms, there are 20 unstable isotopes that have been stud-ied. Xe-129 is produced by beta decay of I-129 (half-life: 16 million years); Xe-131m, Xe-133, Xe-133m, and Xe-135 are fission products of both U-235 and Pu-239, and therefore used as indicators of nuclear explosions. Radioactive xenon isotopes are also found emanating from nuclear reactors.Because Xe is a tracer for two parent isotopes, Xe isotope ratios in meteorites are a

powerful tool for studying the formation of the solar system. The I-Xe method of dat-ing gives the time elapsed between nucleosynthesis and the condensation of a solid object from the solar nebula.Xenon isotopes are also a powerful tool for understanding terrestrial differentiation.

Excess Xe-129 found in carbon dioxide well gases from New Mexico was believed to be from the decay of mantle-derived gases soon after Earth's formation.



Previous Page

Caesium

Caesium (also spelled cesium, though it goes against Latin phonetics) is a chemical element in the periodic table that has the symbol Cs, atomic number 55 .and atomic weight of 132.9054519. It is a Alkaline metal.

• Name: Caesium• Symbol: Cs• Atomic number: 55• Atomic weight: 132.9054519• Standard state: solid at 298 K , but melts only slightly above this tem-

perature• CAS Registry ID: 7440-46-2• Group in periodic table: 1• Group name: Alkali metal• Period in periodic table: 6• Block in periodic table: s-block• Colour: silvery gold• Classification: Metallic

Caesium is a soft silvery-gold Alkali metal which is one of at least three metals that are liquid at room temperature. This element is most notably used in atomic clocks.Caesium is sometimes spelt cesium, especially in North American English, but cae-

sium is the official name preferred by IUPAC, although since 1993 it has recognized cesium as a variant.


The electromagnetic spectrum of caesium has two bright lines in the blue part of the spectrum along with several other lines in the red, yellow, and green. This metal is silvery gold in color and is both soft and ductile. Caesium is also the most electropos-itive and most alkaline chemical element and also has the least ionization potential of all the elements, except for francium. Caesium is the least abundant of the five non-radioactive alkali metals. (Technically, francium is the least common alkali met-al, but since it is highly radioactive with less than an ounce in the entire earth at one time, its abundance can be considered zero in practical terms).Along with gallium and mercury, caesium is among the only metals that are liquid at

or near room temperature. Caesium reacts explosively in cold water and also reacts

with ice at temperatures above -116°C. Caesium hydroxide (CsOH) is the strongest base known to exist and attacks glass.

Applications

Caesium is most notably used in atomic clocks, which are accurate to seconds in many thousands of years.

Other Uses:* Cs-134 has been used in hydrology as a measure of caesium output by the nuclear

power industry. This isotope is used because, while it is less prevalent than either Cs-133 or Cs-137, Cs-134 can be produced solely by nuclear reactions. Cs-135 has also been used in this function. * Like other group 1 elements, caesium has a great affinity for oxygen and is used as

a "getter" in vacuum tubes. * This metal is also used in photoelectric cells. * In addition, caesium is used as a catalyst in the hydrogenation of certain organic

compounds. * Isotopes (radioactive) of Caesium are used in the medical field to treat certain

types of cancer. More recently this metal has been used in ion propulsion systems

History

Caesium (Latin caesius meaning "sky blue") was spectroscopically discovered by Rob-ert Bunsen and Gustav Kirchhoff in 1860 in mineral water from Dürkheim, Germany. Its identification was based upon the bright blue lines in its spectrum and it was the first element discovered by spectrum analysis. The first caesium metal was produced in 1881. Since 1967, the International System of Units (SI) has defined the second as 9,192,631,770 cycles of the radiation which corresponds to the transition between two energy levels of the ground state of the Caesium-133 atom. Historically, the most im-portant use for caesium has been in research and development, primarily in chemical and electrical applications.

Occurrence

An alkali metal, caesium occurs in lepidolite, pollucite (hydrated silicate of aluminium and caesium) and within other sources. One of the world's most significant and rich sources of this metal is located at Bernic Lake in Manitoba. The deposits there are es-timated to contain 300,000 tons of pollucite at an average of 20% caesium.It can be isolated by electrolysis of fused cyanide and in a number of other ways. Ex-

ceptionally pure and gas-free caesium can be made by the thermal decomposition of caesium azide. The primary compounds of caesium are its chloride and its nitrate. The price of caesium in 1997 was about $US 30 per gram.

Isotopes

Caesium has 32 known isotopes which is more than any other element, except fran-cium. The atomic masses of these isotopes range from 114 to 145. Even though this


Previous Page

element has the largest number of isotopes, it only has one naturally occurring stable isotope, Cs-133. The radiogenic isotope Cs-137 has been used in hydrologic studies, analogous to the use of H-3. Cs-137 is produced from detonation of nuclear weapons and emissions from nuclear power plants, and notably from the 1986 Chernobyl ex-plosion. Beginning in 1954 with the commencement of nuclear testing, Cs-137 was released into the atmosphere where it is absorbed readily into solution. Once Cs-137 enters the ground water, it is deposited on soil surfaces and removed from the land-scape primarily by particle transport. As a result, the input function of these isotopes can be estimated as a function of time.


Barium

Barium is a toxic chemical element in the periodic table that has the symbol Ba, atomic number 56 and atomic weight of 137.327 It is a Alkaline Earth Metal.

• Name: Barium• Symbol: Ba• Atomic number: 56• Atomic weight: 137.327• Standard state: solid at 298 K• CAS Registry ID: 7440-39-3• Group in periodic table: 2• Group name: Alkaline earth metal• Period in periodic table: 6• Block in periodic table: s-block• Colour: silvery white• Classification: Metallic

A soft silvery metallic element, barium is an alkaline earth metal and melts at a very high temperature. Its oxide is called baryta and it is primarily found in the mineral barite but is never found in its pure form due to its reactivity with air. Compounds of this metal are used in small quantities in paints and in glassmaking.


Barium is a metallic element that is chemically similar to calcium, yet is soft and in its pure form is silvery white resembling lead. This metal oxidizes very easily and when exposed to air and is highly reactive with water or alcohol. Barium is decomposed by water or alcohol. Some of the compounds of this element are remarkable for their high specific gravity, as is its sulfate: barite Ba(SO4) also called heavy spar.

Applications

Barium is primarily used in sparkplugs, vacuum tubes, fireworks, and in fluorescent lamps. Also a "getter" in vacuum tubes. Barium sulfate is permanent white and is used in paint, in X-ray diagnostic work, and in glassmaking. Barite is used extensively as a weighing agent in oil well drilling fluids and in rubber production. Barium carbonate is a useful rat poison and can also be used in making glass and bricks, while barium


Previous Page

nitrate and chlorate give colors in fireworks. Impure barium sulfide phosphoresces af-ter exposure to the light. Barium salts, especially barium sulfate, are sometimes given orally (a barium meal) or as an enema, to increase the contrast of medical X-rays of the digestive system. Lithopone, a pigment that contains barium sulfate and zinc sulfide, has good covering power, and does not darken in when exposed to sulfides.

History

Barium (Greek "barys" meaning "heavy") was first identified in 1774 by Carl Scheele and extracted in 1808 by Sir Humphry Davy in England. The oxide was at first called barote, by Guyton de Morveau, which was changed by Antoine Lavoisier to baryta, which soon was modified to "barium" to describe the metal.

Occurrence

Because barium quickly becomes oxidized in air, it is difficult to obtain this metal in its pure form. It is primarily found in and extracted from the mineral barite which is crystalized barium sulfate. Barium is commercially produced through the electrolysis of molten barium chloride (BaCl2)CompoundsThe most important compounds are barium peroxide, chloride, sulfate, carbonate,

nitrate, and chlorate. When burned, barium salts glows green.

Isotopes

Naturally occurring barium is a mix of seven stable isotopes. There are twenty-two isotopes known, but most of these are highly radioactive and have half-lifes in the several millisecond to several minute range. The only notable exception is barium-133 which has a half-life of 10.51 years.


Lanthanum

Lanthanum is a chemical element in the periodic table that has the symbol La, atomic number 57 and atomic weight of 138.90547. It is a Lanthanoid.

• Name: Lanthanum• Symbol: La• Atomic number: 57• Atomic weight: 138.90547• Standard state: solid at 298 K• CAS Registry ID: 7439-91-0• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic• Notable characteristics

Lanthanum is a silvery white metallic element belonging to group 3 of the period-ic table and often considered to be one of the lanthanides. Found in some rare-earth minerals, usually in combination with cerium and other rare earth elements. Lantha-num is malleable, ductile, and soft enough to be cut with a knife. It is one of the most reactive of the rare-earth metals. The metal reacts directly with elemental carbon, nitrogen, boron, selenium, silicon, phosphorus, sulfur, and with halogens. It oxidizes rapidly when exposed to air. Cold water attacks lanthanum slowly, while hot water attacks it much more rapidly.

Applications

Uses of lanthanum: * Carbon lighting applications, especially by the motion picture industry for studio

lighting and projection. * La2O3 improves the alkali resistance of glass, and is used in making special optical

glasses, such as: * Infrared absorbing glass. * Camera and telescope lenses, because of the high refractive index and low disper-

sion of rare-earth glasses.


Previous Page

* Small amounts of lanthanum added to steel improves its malleability, resistance to impact and ductility. * Small amounts of lanthanum added to iron helps to produce nodular cast iron. * Small amounts of lanthanum added to molybdenum decreases the hardness of this

metal and its sensitivity to temperature variations. * Mischmetal, a pyrophoric alloy used e.g. in lighter flints, contains 25% to 45% lan-

thanum. * The oxide and the boride are used in electronic vacuum tubes. * Hydrogen sponge alloys can contain lanthanum. These alloys are capable of storing

up to 400 times their own volume of hydrogen gas in a reversible adsorption process. * Petroleum cracking catalysts. * Gas lantern mantles. * Glass and lapidary polishing compound.* La-Ba age dating of rocks and ores. * Lanthanum Nitrate is mainly applied in specialty glass, water treatment and cata-

lyst.

History

Lanthanum was discovered in 1839 by C. G. Mosander, when he partially decomposed a sample of cerium nitrate by heating and treating the resulting salt with dilute nitric acid. From the resulting solution, he isolated a new rare earth he called lantana.Lanthanum was isolated in relatively pure form in 1923. The word lanthanum comes

from the Greek lanthanein, to lie hidden.

Biological RoleLanthanum has no known biological role. The element is not absorbed orally, and

when injected its elimination is very slow. Lanthanum carbonate is being studied as a compound to absorb excess phosphate in cases of end-stage renal failure. Some ra-re-earth chlorides, such as lanthanum chloride (LaCl3), are known to have anticoagu-lant properties.

Occurrence

Monazite (Ce, La, Th, Nd, Y) (PO4), and bastnasite (Ce, La, Y) (CO3 F), are principal ores in which lanthanum occurs in percentages up to 25 percent and 38 percent respective-ly.

Isotopes

Naturally occurring lanthanum is composed of one stable and one radioactive iso-tope; 139-La, and 138-La with the stable isotope, 139-La, being the most abundant (99.91% natural abundance). 31 radioisotopes have been characterized with the most stable being 138-La with a half-life of 1.05E 11 years, and 137-La with a half-life of 60,000 years. All of the remaining radioactive isotopes have half-lifes that are less than 24 hours and the majority of these have half lifes that are less than 1 minute. This ele-ment also has 3 meta states.The isotopes of lanthanum range in atomic weight from

(120 u) (120-La) to (152 u) (152-La).



Previous Page

Cerium

Cerium is a chemical element in the periodic table that has the symbol Ce, atomic number 58 and atomic weight of 140.116. It is a Lanthanoid.

• Name: Cerium• Symbol: Ce• Atomic number: 58• Atomic weight: 140.116• Standard state: solid at 298 K• CAS Registry ID: 7440-45-1• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic• Notable characteristics

Cerium is a silvery metallic element, belonging to the lanthanide group. It is used in some rare-earth alloys. The oxidized form is used in the glass industry. It resembles iron in color and luster, but is soft, and both malleable and ductile. It tarnishes readily in the air.Only europium is more reactive than cerium among rare earth elements. Alkali solu-

tions and dilute and concentrated acids attack the metal rapidly. The pure metal is likely to ignite if scratched with a knife. Cerium decomposes slowly in cold water and rapidly in hot water.Because of the relative closeness of the 4f and outer shell orbitals in cerium, it ex-

hibits an interestingly variable chemistry. For example, compression or cooling of the metal can change its oxidation state from about 3 to 4Cerium in the +3 oxidation state is referred to as cerous, while the metal in the +4 oxi-

dation state is called Cerium (IV) salts are orange red or yellowish, whereas cerium (III) salts are usually white.

Applications

Uses of Cerium: * In metallurgy:

* Cerium is used in making aluminium alloys and some steels and irons. * Adding cerium to cast irons opposes graphitisation and produces a malleable iron. * In steels cerium can help reduce sulfides and oxides and degasifies. * Cerium is used in stainless steel as a precipitation-hardening agent. * 3 to 4% cerium added to magnesium alloys, along with 0.2 to 0.6% zirconium, helps

refine the grain and give sound casting of complex shapes. It also adds heat resistance to magnesium castings. * Cerium is used in alloys that are used to make permanent magnets. * Cerium is used in carbon-arc lighting, especially in the motion picture industry. * Cerium is a component of Mischmetal, which is extensively used in the manufac-

ture of pyrophoric alloys for cigarette lighters. * The oxide is used in incandescent gas mantles. * The oxide is emerging as a hydrocarbon catalyst in self cleaning ovens, incorporat-

ed into oven walls. * Ceric sulfate is used extensively as a volumetric oxidizing agent in quantitative

analysis. * Cerium compounds are used in the manufacture of glass, both as a component and

as a decolorizer. * Cerium compounds are used for the coloring of enamel. * The oxide is finding increased use as a glass polishing agent. * In glass, cerium oxide allows for selective absorption of ultraviolet light. * Cerium oxide is finding use as a petroleum cracking catalyst in petroleum refining. * Cerium(III) and Cerium(IV) compounds have uses as catalysts in organic synthesis

History

Cerium was discovered in Sweden by Jöns Jacob Berzelius and Wilhelm von Hisinger, and independently in Germany by Martin Heinrich Klaproth, both in 1803. Cerium was so named by Berzelius after the asteroid Ceres, discovered two years earlier (1801).

Occurrence

Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust. It is found in a number of minerals including allanite (also known as orthite) - (Ca, Ce, La, Y)2(Al, Fe)3(SiO4)3(OH), monazite (Ce, La, Th, Nd, Y)PO4, bastna-site(Ce, La, Y)CO3F, hydroxylbastnasite (Ce, La, Nd)CO3(OH, F), rhabdophane (Ce, La, Nd)PO4-H2O, and synchysite Ca(Ce, La, Nd, Y)(CO3)2F. Monazite and bastnasite are pres-ently the two most important sources of cerium.Cerium is most often prepared via an ion exchange process that uses monazite sands

as its cerium sourceLarge deposits of monazite, allanite, and bastnasite will supply cerium, thorium, and

other rare-earth metals for many years to comeCompoundsCommon oxidation states of cerium include: Ce4+, Ce(IV)

Isotopes

Naturally occurring cerium is composed of 3 stable isotopes and 1 radioactive isotope;


Previous Page

136-Ce, 138-Ce, 140-Ce, and 142-Ce with 140-Ce being the most abundant (88.48% nat-ural abundance). 27 radioisotopes have been characterized with the most {abundant and/or stable} being 142-Ce with a half-life of 5*10 to the sixteenth - years, 144-Ce with a half-life of 284.893 days, 139-Ce with a half-life of 137.640, and 141-Ce with a half-life of 32.501 days. All of the remaining radioactive isotopes have half-lifes that are less than 4 days and the majority of these have half lifes that are less than 10 minutes. This element also has 2 meta states. The isotopes of cerium range in atomic weight from 123 u (123-Ce) to 152 u (152-Ce)


Praseodymium

Praseodymium is a chemical element in the periodic table that has the symbol Pr, atomic number 59 and atomic weight of 140.90765. It is a Lanthanoid.

• Name: Praseodymium• Symbol: Pr• Atomic number: 59• Atomic weight: 140.90765• Standard state: solid at 298 K• CAS Registry ID: 7440-10-0• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white, yellowish tinge• Classification: Metallic


Praseodymium is a soft silvery metallic element, and belongs to the lanthanide group. It is somewhat more resistant to corrosion in air than europium, lanthanum, cerium, or neodymium, but it does develop a green oxide coating that spalls off when exposed to air, exposing more metal to oxidation. For this reason, praseodymium should be stored under a light mineral oil or sealed in plastic or glass.

Applications

Uses of praseodymium:* As an alloying agent with magnesium to create high-strength metals that are used

in aircraft engines. * Praseodymium forms the core of carbon arc lights which are used in the motion

picture industry for studio lighting and projector lights. * Praseodymium compounds are used to give glasses and enamels a yellow color.

* Praseodymium is a component of didymium glass, which is used to make certain types of welder's and glass blower's goggles.

History


Previous Page

The name Praseodymium comes from the Greek prasios, meaning green, and didy-mos, or twin.In 1841, Mosander extracted the rare earth didymium from lanthana. In 1874, Per Te-

odor Cleve concluded that didymium was in fact two elements, and in 1879, Lecoq de Boisbaudran isolated a new earth, Samarium, from didymium obtained from the min-eral samarskite. In 1885, the Austrian chemist baron C. F. Auer von Welsbach separat-ed didymium into two elements, Praseodymium and Neodymium, which gave salts of different colors.OccurrencePraseodymium is found in the rare earth minerals monazite and bastnasite, and can

be recovered from bastnasite or monazite by an ion-exchange process. Praseodymium also makes up about 5% of Misch metal.

Isotopes

Naturally occurring praseodymium is composed of one stable isotope, 141-Pr. 38 ra-dioisotopes have been characterized with the most stable being 143-Pr with a half-life of 13.57 days and 142-Pr with a half-life of 19.12 hours. All of the remaining radioactive isotopes have half-lifes that are less than 5.985 hours and the majority of these have half lifes that are less than 33 seconds. This element also has 6 meta states with the most stable being 138m-Pr (t1/2 2.12 hours), 142m-Pr (t1/2 14.6 minutes) and 134m-Pr (t1/2 11 minutes).The isotopes of praseodymium range in atomic weight from 120.955 u (121-Pr) to

158.955 u (159-Pr). The primary decay mode before the stable isotope, 141-Pr, is electron capture and the primary mode after is beta minus decay. The primary decay products before 141-Pr are element 58 (Cerium) isotopes and the primary products after are ele-ment 60 (Neodymium) isotopes.


Neodymium

Neodymium is a chemical element in the periodic table that has the symbol Nd, atom-ic number 60 and atomic weight of 144.242. It is a Lanthanoid

• Name: Neodymium• Symbol: Nd• Atomic number: 60• Atomic weight: 144.242• Standard state: solid at 298 K• CAS Registry ID: 7440-00-8• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white, yellowish tinge• Classification: Metallic


Neodymium, a rare earth metal, is present in misch metal to the extent of about 18%. The metal has a bright silvery metallic luster; however, being one of the more reactive rare-earth metals, Neodymium quickly tarnishes in air, forming an oxide that spalls off and exposes the metal to further oxidation.

Applications

Uses of Neodymium include: * Neodymium is a component of didymium used for colouring glass to make welder's

goggles * Neodymium colours glass in delicate shades ranging from pure violet through

wine-red and warm gray. Light transmitted through such glass shows unusually sharp absorption bands; the glass is used in astronomical work to produce sharp bands by which spectral lines may be calibrated. Neodymium is also used to remove the green colour caused by iron contaminants from glass. * Certain transparent materials with a small concentration of neodymium ions can

be used in lasers for infrared wavelengths (1054-1064 nm), e.g. Nd:YAG (yttrium alu-minium garnet), Nd:YLF (yttrium lithium fluoride), Nd:YVO (yttrium vanadate), Nd:-


Previous Page

glass. * Neodymium salts are used as a colourant for enamels. * Neodymium is used in very powerful permanent magnets - Nd2Fe14B. These mag-

nets are cheaper than Samarium-Cobalt magnets and appear in products such as iPod in-ear headphones. * Neodymium ions are used in active laser media.

HistoryNeodymium was discovered by Baron Carl F. Auer von Welsbach, an austrian chemist,

in Vienna in 1885. He separated neodymium, as well as the element Praseodymium, from a material known as didymium; however, it was not isolated in relatively pure form until 1925. The name Neodymium is derived from the greek words neos, new, and didymos, twin.Today, Neodymium is primarily obtained through an ion exchange process of

monazite sand ((Ce,La,Th,Nd,Y)PO4), a material rich in rare earth elements, and through electrolysis of its halide salts.

OccurrenceNeodymium is never found in nature as the free element; rather, it occurs in ores

such as monazite sand ((Ce,La,Th,Nd,Y)PO4) and bastnosite ((Ce,La,Th,Nd,Y)(CO3)F) that contain small amounts of all the rare earth metals. Neodymium can also be found in Misch metal; it is difficult to separate from other rare earth elements.

IsotopesNaturally occurring Neodymium is composed of 5 stable isotopes, 142-Nd, 143-Nd,

145-Nd, 146-Nd and 148-Nd, with 142-Nd being the most abundant (27.2% natural abun-dance), and 2 radioisotopes, 144-Nd and 150-Nd. 31 radioisotopes have been character-ized, with the most stable being 150-Nd with a half-life of 1.1E19 years, 144-Nd with a half-life of 2.29E15 years, and 147-Nd with a half-life of 10.98 days. All of the remaining radioactive isotopes have half-lifes that are less than 3.38 days, and the majority of these have half lifes that are less than 71 seconds. This element also has 4 meta states with the most stable being 139m-Nd (tÂ½ 5.5 hours), 135m-Nd (tÂ½ 5.5 minutes) and 141m-Nd (tÂ½ 62.0 seconds).The primary decay mode before the most abundant stable isotope, 142-Nd, is electron

capture and the primary mode after is beta minus decay. The primary decay products before 142-Nd are element Pr (Praseodymium) isotopes and the primary products after are element Pm (Lead) isotopes.


Promethium

Promethium is a chemical element in the periodic table that has the symbol Pm, atomic number 61 and atomic weight of 145. It is a Lanthanoid.

• Name: Promethium• Symbol: Pm• Atomic number: 61• Atomic weight: 145• Standard state: solid at 298 K• CAS Registry ID: 7440-12-2• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: metallic• Classification: Metallic


Promethium is a soft beta emitter; it does not emit gamma rays, but beta particles impinging on elements of high atomic numbers can generate X-rays. Little is known as of today about the properties of metallic promethium; two allotropic modifications exist, and promethium salts luminesce in the dark with a pale blue or greenish glow due to their high radioactivity.

Applications

Uses for Promethium include:* Beta radiation source for thickness gages. * Light source for signals that require dependable operation (using phosphor to ab-

sorb the beta radiation and produce light). * In a nuclear battery in which photocells convert the light into electric current,

yielding a useful life of about 5 years using 147-Pm. * Possibly in the future as a portable X-ray source, as an auxiliary heat / power

source for space probes and satellites, and to make lasers that can be used to commu-nicate with submerged submarines.


Previous Page

History

The existence of promethium was first predicted by Branner in 1902, this prediction was confirmed by Moseley in 1914. Several groups claimed to have produced the ele-ment, but they could not confirm their discoveries because of the difficulty of sepa-rating Promethium from other elements. Proof of the existence of Promethium was obtained in 1944 only by Jacob A. Marinsky, Lawrence E. Glendenin and Charles D. Coryell during the analysis of byproducts of uranium fission; however, being too busy with defense-related research during World War II, they did not claim their discovery until 1946. The name Promethium is derived from Prometheus from Greek mythology, who stole the fire of the sky and gave it to mankind.In 1963, ion-exchange methods were used to prepare about 10 g of Promethium from

atomic reactor fuel processing wastes. Today, Promethium is still recovered from the byproducts of uranium fission; it can also be produced by bombarding 146-Nd with neutrons, turning it into 147-Nd which decays into 147-Pm through beta decay with a half-life of 11 days.

Occurrence

Promethium does not naturally occur on earth, but has been identified in the spec-trum of the star HR465 in Andromeda.

Isotopes

36 radioisotopes of Promethium have been characterized, with the most stable being 145-Pm with a half-life of 17.7 years, 146-Pm with a half-life of 5.53 years, and 147-Pm with a half-life of 2.6234 years. All of the remaining radioactive isotopes have half-lifes that are less than 364 days, and the majority of these have half lifes that are less than 27 seconds. This element also has 11 meta states with the most stable being 148m-Pm (t1/2 41.29 days), 152m2-Pm (t1/2 13.8 minutes) and 152m-Pm (t1/2 7.52 minutes).The isotopes of Promethium range in atomic weight from 127.9482600 u (128-Pm) to

162.9535200 u (163-Pm). The primary decay mode before the most abundant stable iso-tope, 145-Pm, is electron capture, and the primary mode after is beta minus decay. The primary decay products before 145-Pm are element Nd (Neodymium) isotopes and the primary products after are element Sm (Samarium) isotopes.


SamariumSamarium is a chemical element in the periodic table that has the symbol Sm, atomic

number 62 and atomic weight of 150.36. It is a Lanthanoid.

• Name: Samarium• Symbol: Sm• Atomic number: 62• Atomic weight: 150.36• Standard state: solid at 298 K• CAS Registry ID: 7440-19-9• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic

Notable CharacteristicsSamarium is a rare earth metal, with a bright silver lustre, that is reasonably stable in

air; it ignites in air at 150°C. Three crystal modifications of the metal also exist, with transformations at 734 and 922°C, respectively.

Applications

Uses of Samarium include:* Carbon-arc lighting for the motion picture industry (together with other rare

earth metals). * Doping CaF2 crystals for use in optical masers or lasers. * As a neutron absorber in nuclear reactors. * For alloys and headphones. * Samarium-Cobalt magnets; SmCo5 is used in making a new permanent magnet ma-

terial with the highest resistance to demagnetization of any known material, and an intrinsic coercive force as high as 2200 kA/m. * Samarium oxide is used in optical glass to absorb infrared light. * Samarium compounds act as sensitizers for phosphors excited in the infrared. * Samarium oxide is catalytic for the dehydration and dehydrogenation of ethanol.


Previous Page

History

Samarium was first discovered spectroscopically in 1853 by swiss chemist Jean Charles Galissard de Marignac by its sharp absorption lines in didymium, and isolated in Paris in 1879 by french chemist Paul Émile Lecoq de Boisbaudran from the mineral samar-skite ((Y,Ce,U,Fe)3(Nb,Ta,Ti)5O16). Like the mineral, it was named after a Russian mine official, Colonel Samarski.

Biological RoleSamarium has no known biological role, but is said to stimulate the metabolism.

OccurrenceSamarium is never found free in nature, but, like other rare earth elements, is con-

tained in many minerals, including monazite, bastnasite and samarskite; monazite (in which it occurs up to an extent of 2.8%) and bastnasite are also used as commer-cial sources. Misch metal containing about 1% of Samarium has long been used, but it was not until recent years that relatively pure Samarium has been isolated through ion-exchange processes, solvent extraction techniques, and electrochemical deposi-tion. Samarium can also be obtained by reducing its oxide with Lanthanum.

IsotopesNaturally occurring Samarium is composed of 4 stable isotopes, 144-Sm, 150-Sm, 152-

Sm and 154-Sm, and 3 radioisotopes, 147-Sm, 148-Sm and 149-Sm, with 152-Sm being the most abundant (26.75% natural abundance). 32 radioisotopes have been characterized, with the most stable being 148-Sm with a half-life of 7E+15 years, 149-Sm with a half-life of more than 2E+15 years, and 147-Sm with a half-life of 1.06E+11 years.All of the remaining radioactive isotopes have half-lifes that are less than 1.04E+8

years, and the majority of these have half lifes that are less than 48 seconds. This el-ement also has 5 meta states with the most stable being 141m-Sm (t1/2 22.6 minutes), 143m1-Sm (t1/2 66 seconds) and 139m-Sm (t1/2 10.7 seconds).The primary decay mode before the most abundant stable isotope, 152-Sm, is electron

capture, and the primary mode after is beta minus decay. The primary decay products before 152-Sm are element Pm (Promethium) isotopes, and the primary products after are element Eu (Europium) isotopes.


Europium

Europium is a chemical element in the periodic table that has the symbol Eu, atomic number 63 and atomic weight of 151.964. It is a Lanthanoid.

• Name: Europium• Symbol: Eu• Atomic number: 63• Atomic weight: 151.964• Standard state: solid at 298 K• CAS Registry ID: 7440-53-1• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic


Europium is the most reactive of the rare earth elements; it quickly oxidizes in air, and resembles Calcium in its reaction with water. Like other rare earths (with the exception of Lanthanum, Europium ignites in air at about 150 to 180Â°. It is about as hard as lead and quite ductile.

Applications

There are no commercial applications for Europium metal, although it has been used to dope some types of plastics to make lasers. Due to its ability to absorb neutrons, it is also being studied for use in nuclear reactors. Europium Oxide (Eu2O3) is widely used as a red phosphor in television sets, and as an activator for Yttrium-based phos-phors.

History

Europium was first found by Paul Émile Lecoq de Boisbaudran in 1890, who obtained basic fraction from Samarium-Gadolinium concentrates which had spectral lines not accounted for by Samarium or Gadolinium; however, the discovery of Europium is


Previous Page

generally credited to french chemist Eugêne-Antole Demarcay, who suspected sam-ples of the recently discovered element Samarium were contaminated with an un-known element in 1896 and who was able to isolate Europium in 1901. Pure Europium metal was not isolated until recent years.

Occurrence

Europium is never found in nature as the free element; however, there are many minerals containing Europium, with the most important sources being bastnasite and monazite. Europium has also been identified in the spectra of the sun and certain stars.

Isotopes

Naturally occurring Europium is composed of 2 stable isotopes, 151-Eu and 153-Eu, with 153-Eu being the most abundant (52.2% natural abundance). 35 radioisotopes have been characterized, with the most stable being 150-Eu with a half-life of 36.9 years, 152-Eu with a half-life of 13.516 years, and 154-Eu with a half-life of 8.593 years. All of the remaining radioactive isotopes have half-lifes that are less than 4.7612 years, and the majority of these have half lifes that are less than 12.2 seconds. This element also has 8 meta states, with the most stable being 150m-Eu (t1/2 12.8 hours), 152m1-Eu (t1/2 9.3116 hours) and 152m2-Eu (t1/2 96 minutes).The primary decay mode before the most abundant stable isotope, 153-Eu, is electron

capture, and the primary mode after is beta minus decay. The primary decay products before 153-Eu are element Sm (Samarium) isotopes and the primary products after are element Gd (Gadolinium) isotopes.


Gadolinium

Gadolinium is a chemical element in the periodic table that has the symbol Gd, atom-ic number 64 and atomic weight of 157.25. It is a Lanthanoid.

• Name: Gadolinium• Symbol: Gd• Atomic number: 64• Atomic weight: 157.25• Standard state: solid at 298 K• CAS Registry ID: 7440-54-2• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic


Gadolinium is a silvery white, malleable and ductile rare earth metal with a metal-lic luster. It crystalizes in hexagonal, close-packed alpha form at room temperature; when heated to 1508 K, it transforms into its beta form, which has a body-centered cubic structure.Unlike other rare earth elements, Gadolinium is relatively stable in dry air; however,

it tarnishes quickly in moist air and forms a losely adhering oxide that spalls off and exposes more surface to oxidation. Gadolinium reacts slowly with water and is soluble in dilute acid.Gadolinium also has the highest thermal neutron capture cross-section of any

(known) element, 49,000 barns, but it also has a fast burn-out rate, limiting its useful-ness as a nuclear control rod material.Gadolinium becomes superconductive below a critical temperature of 1.083 K it is

strongly magnetic at room temperature, and is in fact the only metal to exhibit ferro-magnetic properties except for fourth period transition metals.

Applications

Gadolinium is used for making gadolinium yttrium garnets, which have microwave


Previous Page

applications; gadolinium compounds also are used for making phosphors for colour TV tubes, and solutions of compounds are used as intravenous contrasts to enhance images in patients undergoing magnetic resonance imaging. Gadolinium is also used for manufacturing compact discs and computer memory.Gadolinium also possesses unusual superconductive properties, with as little as 1% of

Gadolinium improving the workability and resistance of Iron, Chromium and related alloys to high temperatures and oxidation.In the future, Gadolinium ethyl sulfate, which has extremely low noise characteris-

tics, may be used in masers; furthermore, Gadolinium's high magnetic movement and its Curie temperature which lies just at room temperature suggest applications as a magnetic component for sensing hot and cold.

History

In 1880, Swiss chemist Jean Charles Galissard de Marignac observed spectroscopic lines due to Gadolinium in samples of didymium and gadolinite; French chemist Paul Émile Lecoq de Boisbaudran separated gadolinia, the oxide of Gadolinium, from Mo-sander's yttria in 1886. The element itself was isolated only recently for the first time.Gadolinium, like the mineral gadolinite, is named after Finnish chemist and geologist

Johan Gadolin.

Biological Role

Gadolinium has no known biological role, but is said to stimulate the metabolism.

Occurrence

Gadolinium is never found in nature as the free element, but is contained in many minerals such as gadolinite, monazite and bastnasite. Today, it is prepared by ion exchange and solvent extraction technique, or by the reduction of its anhydrous fluo-ride with metallic Calcium.

Isotopes

Naturally occurring Gadolinium is composed of 5 stable isotopes, 154-Md, 155-Md, 156-Md, 157-Md and 158-Md, and 2 radioisotopes, 152-Md and 160-Md, with 158-Md being the most abundant (24.84% natural abundance). 30 radioisotopes have been characterized with the most stable being 160-Md with a half-life of 1.3E+21 years, 152-Md with a half-life of 1.08E+14 years, and 150-Md with a half-life of 1.79E+6 years. All of the remaining radioactive isotopes have half-lifes that are less than 74.7 years, and the majority of these have half lifes that are less than 24.6 seconds. This element also has 4 meta states with the most stable being 143m-Gd (t1/2 110 seconds), 145m-Gd (t1/2 85 seconds) and 141m-Gd (t1/2 24.5).The primary decay mode before the most abundant stable isotope, 158-Gd, is electron

capture and the primary mode after is beta minus decay. The primary decay products before 158-Gd are element Eu (Europium) isotopes and the primary products after are element Tb (Terbium) isotopes.



Previous Page

Terbium

Terbium is a chemical element in the periodic table that has the symbol Tb, atomic number 65 and atomic weight of 158.92535. It is a Lanthanoid.

• Name: Terbium• Symbol: Tb• Atomic number: 65• Atomic weight: 158.92535• Standard state: solid at 298 K• CAS Registry ID: 7440-27-9• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic


Terbium is a silvery-gray rare earth metal that is malleable, ductile and soft enough to be cut with a knife. It is reasonably stable in air, and two crystal modifications ex-ist, with a transformation temperature of 1289°C.

Applications

Terbium is used to dope Calcium fluoride, calcium tungstate and Strontium molyb-date, materials that are used in solid-state devices, and as a crystal stabilizer of fuel cells which operate at elevated temperatures, together with ZrO2. Terbium is also used in alloys and in the production of electronic devices, its oxide is used in green phosphors in fluorescent lamps and color TV tubes. Sodium Terbium borate is used as a laser material that emits coherent light at 5460 Å.

History

Terbium was discovered by Swedish chemist Carl Gustaf Mosander in 1843 and named after the village Ytterby in Sweden, who detected it as an impurity in Yttrium-oxide, Y2O3. It was not isolated in pure form until the recent advent of ion-exchange tech-

niques.

Occurrence

Terbium is never found in nature as the free element, but it is contained in many minerals, including cerite, gadolinite, monazite (Ce,LaTh,Nd,Y)PO4, which contains up to 0.03% of Terbium), xenotime (YPO4) and euxenite (Y,Ca,Er,La,Ce,U,Th)(Nb,Ta,Ti)2O6, which contains 1% or more of Terbium).

Isotopes

Naturally occurring Terbium is composed of 1 stable isotope, 159-Tb. 33 radioisotopes have been characterized, with the most stable being 158-Tb with a half-life of 180 years, 157-Tb with a half-life of 71 years, and 160-Tb with a half-life of 72.3 days.All of the remaining radioactive isotopes have half-lifes that are less than 6.907 days,

and the majority of these have half lifes that are less than 24 seconds. This element also has 18 meta states, with the most stable being 156m1-Tb (t1/2 24.4 hours), 154m2-Tb (t1/2 22.7 hours) and 154m1-Tb (t1/2 9.4 hours).The primary decay mode before the most abundant stable isotope, 159-Tb, is electron

capture, and the primary mode after is beta minus decay. The primary decay products before 159-Tb are element Gd (Gadolinium) isotopes, and the primary products after are element Dy (Dysprosium) isotopes.



Previous Page

Dysprosium

Dysprosium is a chemical element in the periodic table that has the symbol Dy, atom-ic number 66 and atomic weight of 162.5. It is a Lanthanoid.

• Name: Dysprosium• Symbol: Dy• Atomic number: 66• Atomic weight: 162.500• Standard state: solid at 298 K• CAS Registry ID: 7429-91-6• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic


Dysprosium is a rare earth element that has a metallic, bright silver luster, relative-ly stable in air at room temperature, but dissolving readily in dilute or concentrated mineral acids with the emission of hydrogen. It is soft enough to be cut with a knife, and can be machined without sparking if overheating is avoided. Dysprosium's char-acteristics can be greatly affected even by small amounts of impurities.

Applications

Dysprosium is used, in conjunction with vanadium and other elements, for making laser materials; its high thermal neutron absorption cross-section and melting point also suggest using it for nuclear control rods, dysprosium oxide (also known as dys-prosia) with nickel cement compounds which absorb neutrons readily without swell-ing or contracting under prolonged neutron bombardment, is being used for cooling rods in nuclear reactors. Dysprosium-cadmium chalcogenides are sources of infrared radiation for studying chemical reactions; furthermore, dysprosium is used for manu-facturing compact discs.

History

Dysprosium was first identified in Paris in 1886 by French chemist Paul Émile Lecoq de Boisbaudran; however, the element itself was not isolated in relatively pure form until after the development of ion exchange and metallographic reduction techniques in the 1950s. The name dysprosium is derived from Greek dysprositos, "hard to get at".

Occurrence

Dysprosium is never encountered as the free element, but is found in many miner-als, including xenotime, fergusonite, gadolinite, euxenite, polycrase, blomstrandine, monazite and bastnasite, often with erbium and holmium or other rare earth ele-ments.

Isotopes

Naturally occurring dysprosium is composed of 7 stable isotopes, 156-Dy, 158-Dy, 160-Dy, 161-Dy, 162-Dy, 163-Dy and 164-Dy, with 164-Dy being the most abundant (28.18% natural abundance). 28 radioisotopes have been characterized, with the most stable being 154-Dy with a half-life of 3.0E+6 years, 159-Dy with a half-life of 144.4 days, and 166-Dy with a half-life of 81.6 hours. All of the remaining radioactive isotopes have half-lifes that are less than 10 hours, and the majority of these have half lifes that are less than 30 seconds. This element also has 5 meta states, with the most stable being 165m-Dy (t1/2 1.257minutes), 147m-Dy (t1/2 55.7 seconds) and 145m-Dy (t1/2 13.6 seconds).The primary decay mode before the most abundant stable isotope, 164-Dy, is electron

capture, and the primary mode after is beta minus decay. The primary decay products before 164-Dy are terbium isotopes, and the primary products after are holmium iso-topes.



Previous Page

Holmium

Holmium is a chemical element in the periodic table that has the symbol Ho, atomic number 67 and atomic weight of 164.93032. It is a Lanthanoid.

• Name: Holmium• Symbol: Ho• Atomic number: 67• Atomic weight: 164.93032• Standard state: solid at 298 K• CAS Registry ID: 7440-60-0• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic

Part of the lanthanide series, holmium is a relatively soft and malleable silvery-white metallic element, which is stable in dry air at room temperature. A rare earth metal, it is found in the minerals monazite and gadolinite.


A trivalent metallic rare earth element, holmium has the highest magnetic moment (10.6µB) of any naturally-occurring element and possesses other unusual magnetic properties. When combined with yttrium, it forms highly magnetic compounds.Holmium is a relatively soft and malleable element that is fairly corrosion-resistant

and stable in dry air at standard temperature and pressure. In moist air and at higher temperatures, however, it quickly oxidizes, forming a yellowish oxide). In pure form, holmium possesses a metallic, bright silvery luster.

Applications

Because of its magnetic properties, holmium has been used to create the strongest artificially-generated magnetic fields when placed within high-strength magnets as a magnetic pole piece (also called a magnetic flux concentrator). Since it can absorb nuclear fission-bred neutrons, the element is also used in nuclear control rods.

Other commercial applications of the element include:* High magnetic moment is suitable for use in yttrium-iron-garnet (YIG) and yttri-

um-lanthanum-fluoride (YLF) solid state lasers found in microwave equipment (which are in turn found in a variety of medical and dental settings). * Holmium oxide is used as a yellow glass coloring. Few other uses have been identi-

fied for this element.

History

Holmium (Holmia, Latin name for Stockholm) was discovered by Marc Delafontaine and Jacques Louis Soret in 1878 who noticed the aberrant spectrographic absorption bands of the then-unknown element (they called it "Element X"). Later in 1878, Per Teodor Cleve independently discovered the element while he was working on erbia earth (erbium oxide).Using the method developed by Carl Gustaf Mosander, Cleve first removed all of the

known contaminants from erbia. The result of that effort was two new materials, one brown and one green. He named the brown substance holmia (after the Latin name for Cleve's home town, Stockholm) and the green one thulia. Holmia was later found to be the holmium oxide and thulia was thulium oxide.

Occurrence

Like all other rare earths, holmium is not naturally found as a free element. It does occur combined with other elements in the minerals gadolinite, monazite, and in oth-er rare-earth minerals. It is commercially extracted via ion-exchange from monazite sand (0.05% holmium) but is still difficult to separate from other rare earths.The element has been isolated through the reduction of its anhydrous chloride or

fluoride with metallic calcium. Its estimated abundance in the Earth's crust is 1.3 milli-grams per kilogram.



Previous Page

ErbiumErbium is a chemical element in the periodic table that has the symbol Er, atomic

number 68 and atomic weight of 167.259. It is a Lanthanoid.

• Name: Erbium• Symbol: Er• Atomic number: 68• Atomic weight: 167.259• Standard state: solid at 298 K• CAS Registry ID: 7440-52-0• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic

A rare silvery metallic lanthanide rare earth element, erbium is associated with sev-eral other rare elements in the mineral gadolinite from Ytterby in Sweden.

Notable CharacteristicsA trivalent element, pure erbium metal is malleable, soft, somewhat stable in air and

does not oxidize as quickly as some other rare-earth metals. Its salts are rose-colored and the element gives a characteristic sharp absorption spectra in visible light, ultra-violet, and near infrared. Otherwise it looks pretty much like the other rare earths. Its sesquioxide is called erbia. Erbium's properties are a to a degree dictated by the kind and amount of impurities present. Erbium does not play any known biological role but is thought by some to be able to stimulate metabolism.

ApplicationsErbium's everyday uses are varied; commonly it is used as a photographic filter and

because of its resilience it is useful as an metallurgical additive.

Other uses:* Used in nuclear technology as a neutron absorber. * Used as a dopant in Fiber amplifiers. * When added to vanadium as an alloy erbium lowers hardness and improves work-

ability. * Erbium oxide has a pink color and is therefore sometimes used as a glass and por-

celain enamel glaze colorant. The glass is then often used in sunglasses and cheap jewelry.

History

Erbium (for Ytterby, a town in Sweden) was discovered by Carl Gustaf Mosander in 1843. Mosander separated "yttria" from the mineral gadolinite into three fractions which he called yttria, erbia, and terbia. He named the new element after the town of Ytterby where large concentrations of yttria and erbium are located. Erbia and terbia, however, were confused in at this time. After 1860, what had been known as terbia was renamed erbia and after 1877 what had been known as erbia was renamed terbia. Fairly pure Er2O3 was independently isolated in 1905 by Georges Urbain and Charles James. Reasonably pure metal wasn't produced until 1934 when workers reduced the anhydrous chloride with potassium vapor.

OccurrenceLike other rare earths, this element is never found as a free element in nature but is

found bound monazite sand ores. It has historically been very difficult and expensive to separate rare earths from each other in their ores but ion-exchange production techniques developed in the late 20th century have greatly brought down the cost of production of all rare-earth metals and their chemical compounds. The principle commercial sources of erbium are from the minerals xenotime and euxenite. Metallic erbium in dust form presents a fire and explosion hazard.

IsotopesNaturally occurring erbium is composed of 6 stable isotopes, Er-162, Er-164, Er-166, Er-

167, Er-168, and Er-170 with Er-166 being the most abundant (33.6% natural abundance). 23 radioisotopes have been characterized, with the most stable being Er-169 with a half life of 9.4 days, Er-172 with a half-life of 49.3 hours, Er-160 with a half-life of 28.58 hours, Er-165 with a half-life of 10.36 hours, and Er-171 with a half life of 7.516 hours. All of the remaining radioactive isotopes have half-lifes that are less than 3.5 hours, and the majority of these have half lifes that are less than 4 minutes. This element also has 6 meta states, with the most stable being Er-167m (t1/2 2.269 seconds).The isotopes of erbium range in atomic weight from 144.957 amu (Er-145) to 173.944

amu (Er-174). The primary decay mode before the most abundant stable isotope, Er-166, is electron capture, and the primary mode after is beta decay. The primary decay products before Er-166 are element 67 (holmium) isotopes, and the primary products after are element 69 (thulium) isotopes.


Previous Page

From Wikipedia, the free encyclopedia and webelements Thulium

Thulium is a chemical element, in the periodic table that has the symbol Tm, atomic number 69 and atomic weight of 168.93421. It is a Lanthanoid.

• Name: Thulium• Symbol: Tm• Atomic number: 69• Atomic weight: 168.93421• Standard state: solid at 298 K• CAS Registry ID: 7440-30-4• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic

A lanthanide element, thulium is the least abundant of the rare earths and its metal is easy to work, has a bright silvery-gray luster and can be cut by a knife. It also has some corrosion resistance in dry air and good ductility. Naturally occurring thulium is made entirely of the stable isotope Tm-169.

Applications

Thulium has been used to create lasers but high production costs have prevented other commercial uses from being developed.

Other uses/potential uses:* When stable thulium (Tm-169) is bombarded in a nuclear reactor it can later serve

as a radiation source in portable X-ray devices. * The unstable Tm-171 could possibly be used as an energy source. * Tm-169 has potential use in ceramic magnetic materials called ferrites, which are

used in microwave equipment.

History

Thulium was discovered by Swedish chemist Per Teodor Cleve in 1879 by looking for


Previous Page

impurities in the oxides of other rare earth elements (this was the same method Carl Gustaf Mosander earlier used to discover some other rare earths elements). Cleve started by removing all of the known contaminants of erbia (Er2O3) and upon addi-tional processing, obtained two new substances; one brown and one green. The brown substance turned out to be the oxide of the element holmium and was named holmia by Cleve and the green substance was the oxide of an unknown element. Cleve named the oxide thulia and its element thulium after Thule, an ancient Roman name for a mythical country in the far north, perhaps Scandinavia.

Occurrence

The element is never found in found in nature in pure form but it is found in small quantities in minerals with other rare earths. It is principally extracted from monazite (~0.007% thulium) ores found in river sands through ion-exchange. Newer ion-ex-change and solvent extraction techniques have led to easier separation of the rare earths, which has yielded much lower costs for thulium production. The metal can be isolated through reduction of its oxide with lanthanum metal or by calcium reduction in a closed container. None of thulium's compounds are commercially important.

Isotopes

Naturally occurring thulium is composed of 1 stable isotope, Tm-169 (100% natural abundance). 31 radioisotopes have been characterized, with the most stable being Tm-171 with a half-life of 1.92 years, Tm-170 with a half-life of 128.6 days, Tm-168 with a half-life of 93.1 days, and Tm-167 with a half-life of 9.25 days.All of the remaining radioactive isotopes have half-lifes that are less than 64 hours,

and the majority of these have half lifes that are less than 2 minutes. This element also has 14 meta states, with the most stable being Tm-164m (t1/2 5.1 minutes), Tm-160m (t1/2 74.5 seconds) and Tm-155m (t 45 seconds).The isotopes of thulium range in atomic weight from 145.966 u (Tm-146) to 176.949 u

(Tm-177). The primary decay mode before the most abundant stable isotope, Tm-169, is electron capture, and the primary mode after is beta emission. The primary decay products before Tm-169 are element 68 (erbium) isotopes, and the primary products after are element 70 (ytterbium) isotopes.


YtterbiumYtterbium is a soft, malleable and rather ductile element in the periodic table that

has the symbol Yb, atomic number 70 and atomic weight of 173.054. It is a Lanthanoid.

• Name: Ytterbium• Symbol: Yb• Atomic number: 70• Atomic weight: 173.054• Standard state: solid at 298 K• CAS Registry ID: 7440-64-4• Group in periodic table:• Group name: Lanthanoid• Period in periodic table: 6 (lanthanoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic

It exhibits a bright silvery luster. A rare earth element, it is easily attacked and dis-solved by mineral acids, slowly reacts with water, and oxidizes in air.

Notable CharacteristicsYtterbium has three allotropes which are called alpha, beta and gamma and whose

transformation points are at -13°C and 795 °C. The beta form exists at room tempera-ture and has a face-centered crystal structure while the high-temperature gamma form has a body-centered crystal structure.Normally, the beta form has a metallic-like electrical conductivity, but becomes a

semiconductor when exposed to around 16,000 atm. Its electrical resistance is tenfold larger at about 39,000 atm but then dramatically drops to around 10% of its room tem-perature resistivity value at 40,000 atm.

Applications

One ytterbium isotope has been used as a radiation source substitute for a portable X-ray machine when electricity was not available. Its metal could also be used to help improve the grain refinement, strength, and other mechanical properties of stainless steel. Some ytterbium alloys have been used in dentistry. There are few other uses of this element, e.g. in the form of ions in active laser media.


Previous Page

History

Ytterbium was discovered by the Swiss chemist Jean Charles Galissard de Marignac in 1878. Marignac found a new component in the earth then known as erbia and named it ytterbia (after Ytterby, the Swedish town where he found the new erbia component). He suspected that ytterbia was a compound of a new element he called ytterbium (which was in fact the first rare earth to be discovered).In 1907, the French chemist Georges Urbain separated Marignac's ytterbia into two

components, neoytterbia and lutecia. Neoytterbia would later become known as the element ytterbium and lutecia would later be known as the element lutetium. Auer von Welsbach independently isolated these elements from ytterbia at about the same time but called them aldebaranium and cassiopeium.The chemical and physical properties of ytterbium could not be determined until 1953

when the first nearly pure ytterbium was produced.

OccurrenceYtterbium is found with other rare earth elements in several rare minerals. It is most

often recovered commercially from monazite sand (~0.03% ytterbium). The element is also found in euxenite and xenotime. Ytterbium is normally difficult to separate from other rare earths but ion-exchange and solvent extraction techniques developed in the late 20th century have simplified separation. Compounds of ytterbium are rare.

IsotopesNaturally occurring ytterbium is composed of 7 stable isotopes, Yb-168, Yb-170, Yb-171,

Yb-172, Yb-173, Yb-174, and Yb-176, with Yb-174 being the most abundant (31.8% natural abundance). 22 radioisotopes have been characterized, with the most stable being Yb-169 with a half-life of 32.026 days, Yb-175 with a half-life of 4.185 days, and Yb-166 with a half life of 56.7 hours. All of the remaining radioactive isotopes have half-lifes that are less than 2 hours, and the majority of these have half lifes that are less than 20 minutes. This element also has 6 meta states, with the most stable being Yb-169m (t1/2 46 seconds).The isotopes of ytterbium range in atomic weight from 150.955 u (Yb-151) to 179.952

u (Yb-180). The primary decay mode before the most abundant stable isotope, Yb-174 is electron capture, and the primary mode after is beta emission. The primary decay products before Yb-174 are element 69 (thulium) isotopes, and the primary products after are element 71 (lutetium) isotopes.


Lutetium

Lutetium is a chemical element in the periodic table that has the symbol Lu, atomic number 71 and atomic weight of 174.9668. It is a Lanthanoid.

• Name: Lutetium• Symbol: Lu• Atomic number: 71• Atomic weight: 174.9668• Standard state: solid at 298 K• CAS Registry ID: 7439-94-3• Group in periodic table: 3• Group name: (none)• Period in periodic table: 6• Block in periodic table: d-block• Colour: silvery white• Classification: Metallic

A metallic element of the rare earth group, lutetium usually occurs in association with yttrium and is sometimes used in metal alloys and as a catalyst in various pro-cesses.


Lutetium is a silvery white corrosion-resistant trivalent metal that is relatively stable in air and is the heaviest and hardest of the rare earth elements.This element is very expensive to obtain in useful quantities and therefore it has very

few commercial uses. However, stable lutetium can be used as catalysts in petroleum cracking in refineries and can also be used in alkylation, hydrogenation, and polymer-ization applications.

History

Lutetium (Latin Lutetia meaning Paris) was independently discovered in 1907 by French scientist Georges Urbain and Austrian mineralogist Baron Carol Auer von Welsbach. Both men found lutetium as an impurity in the mineral ytterbia which was thought by Swiss chemist Jean Charles Galissard de Marignac (and most others) to consist entirely of the element ytterbium.


Previous Page

The separation of lutetium from Marignac's ytterbium was first described by Urbain and the naming honor therefore went to him. He chose the names neoytterbium (new ytterbium) and lutecium for the new element but neoytterbium was eventually re-verted back to ytterbium and in 1949 the spelling of element 71 was changed to lute-tium.Welsbach proposed the names cassiopium for element 71 (after the constellation Cas-

siopeia) and albebaranium for the new name of ytterbium but these naming proposals where rejected (although many German scientists still call element 71 cassiopium).

Occurrence

Found with almost all other rare-earth metals but never by itself, lutetium is very difficult to separate from other elements and is the least abundant of all naturally-oc-curring elements.The principal commercially viable ore of lutetium is the mineral monzonite [(Ce, La,

etc.)PO4] which contains 0.003% of the element. Pure lutetium metal has only relative-ly recently been isolated and is very difficult to prepare (thus it is one of the most rare and expensive of the rare earth metals). It is separated from other rare earth elements by ion exchange (reduction of anhydrous LuCl3 or LuF3 by either an alkali metal or alkaline earth metal)

Isotopes

Naturally occurring lutetium is composed of 1 stable isotope Lu-175 (97.41% natural abundance). 33 radioisotopes have been characterized, with the most stable being Lu-176 with a half-life of 3.78 Ã— 1010 years (2.59% natural abundance), Lu-174 with a half-life of 3.31 years, and Lu-173 with a half-life of 1.37 years. All of the remaining ra-dioactive isotopes have half-lifes that are less than 9 days, and the majority of these have half lifes that are less than a half an hour. This element also has 18 meta states, with the most stable being Lum-177 (t1/2 160.4 days), Lum-174 (t1/2 142 days) and Lum-178 (t1/2 23.1 minutes).The isotopes of lutetium range in atomic weight from 149.973 u (Lu-150) to 183.961 u

(Lu-184). The primary decay mode before the most abundant stable isotope, Lu-175, is electron capture (with some alpha and positron emission), and the primary mode after is beta emission. The primary decay products before Lu-175 are element 70 (ytterbium) isotopes and the primary products after are element 72 (hafnium) isotopes.


HafniumHafnium is a chemical element in the periodic table that has the symbol Hf, atomic

number 72 and atomic weight of 178.49. It is a Transition Metal.

• Name: Hafnium• Symbol: Hf• Atomic number: 72• Atomic weight: 178.49• Standard state: solid at 298 K• CAS Registry ID: 7440-58-6• Group in periodic table: 4• Group name: (none)• Period in periodic table: 6• Block in periodic table: d-block• Colour: grey steel• Classification: Metallic

A lustrous, silvery gray tetravalent transition metal, hafnium resembles zirconium chemically and is found in zirconium minerals. Hafnium is used in tungsten alloys in filaments and electrodes and also acts as a neutron absorber in nuclear control rods.

Notable CharacteristicsThis is a shiny silvery, ductile metal that is corrosion resistant and chemically simi-

lar to zirconium. The properties of hafnium are markedly affected by zirconium im-purities and these two elements are amongst the most difficult to separate. The only notable difference between them is their density (zirconium is about half as dense as hafnium).Hafnium carbide is the most refractory binary compound known and hafnium nitride

is the most refractory of all known metal nitrides with a melting point of 3310°C). This metal is resistant to concentrated alkalis, but halogens react with it to form hafnium tetrahalides. At higher temperatures hafnium reacts with oxygen, nitrogen, carbon, boron, sulfur, and silicon. The nuclear isomer Hf-178-2m is also a source of energetic gamma rays, and is being studied as a possible power source for gamma ray lasers

ApplicationsHafnium is used to make nuclear control rods, such as those found in nuclear subma-

rines because of its ability to absorb neutrons (its thermal neutron absorption cross


Previous Page

section is nearly 600 times that of zirconium), excellent mechanical properties and exceptional corrosion-resistance properties.

Other uses: * Used in gas-filled and incandescent lamps. * For scavenging oxygen and nitrogen. * As the electrode in plasma cutting because of its ability to shed electrons into air. * Iron, titanium, niobium, tantalum, and other metal alloys. * Hafnium Oxide is a candidate for High-K gate insulators in future generations of

integrated circuits. * Recently, hafnium has been put into development of newer nuclear weapons by

the U.S. government. * DARPA has been intermittently funding programs to determine the possibility

of using a nuclear isomer of hafnium (the above mentioned Hf-178-2m) to construct small, high yield weapons with simple x-ray triggering mechanisms - the hafnium bomb. There is considerable scientific opposition to this program, both on technical and moral grounds (the argument is that though a hafnium bomb might be infeasable, other countries will use an imagined "isomer weapon gap" to justify nuclear weapons development stockpiling).

HistoryHafnium (Latin Hafnia for "Copenhagen") was discovered by Dirk Coster and Georg

von Hevesy in 1923 in Copenhagen, Denmark. Soon after, the new element was pre-dicted to be associated with zirconium by using the Bohr theory and was finally found in zircon through X-ray spectroscope analysis in Norway.It was separated from zirconium through repeated recrystallization of double ammo-

nium or potassium fluorides by Jantzen and von Hevesey. Metallic hafnium was first prepared by Anton Eduard van Arkel and Jan Hendrik deBoer by passing tetraiodide vapor over a heated tungsten filament.

OccurrenceHafnium is found combined in natural zirconium compounds but does not exist as a

free element in nature. Minerals that contain zirconium, such as alvite [(Hf, Th, Zr)SiO4 H2O], thortveitite and zircon (ZrSiO4), usually contain between 1 and 5 percent haf-nium. Hafnium and zirconium have nearly identical chemistry, which makes the two difficult to separate.About half of all hafnium metal manufactured is produced by a by-product of zirconi-

um refinement. This is done through reducing hafnium tetrachloride with magnesium or sodium in the Kroll Process.


Tantalum

Tantalum (formerly tantalium) is a chemical element in the periodic table that has the symbol Ta, atomic number 73 and atomic weight of 180.94788. It is a Transition metal.

• Name: Tantalum• Symbol: Ta• Atomic number: 73• Atomic weight: 180.94788• Standard state: solid at 298 K• CAS Registry ID: 7440-25-7• Group in periodic table: 5• Group name: (none)• Period in periodic table: 6• Block in periodic table: d-block• Colour: grey blue• Classification: Metallic

A rare, hard, blue-gray, lustrous, transition metal, tantalum is highly corrosion-resis-tant and occurs in the mineral tantalite. Tantalum is used in surgical instruments and implants because it does not react with body fluids.


Tantalum is gray, heavy, ductile, very hard, easily fabricated, highly resistant to cor-rosion by acids, and is a good conductor of heat and electricity. In fact, at tempera-tures below 150°C tantalum is almost completely immune to chemical attack, even by the very agressive aqua regia, and can only be attacked by hydrofluoric acid, acidic solutions containing the fluoride ion, and free sulfur trioxide. The element has a melt-ing point exceeded only by tungsten and rhenium (melting point 3290 K, boiling point 5731 K). Tantalum has the most capacitance per volume of any substance.

ApplicationsThe major use for tantalum, as tantalum metal powder, is in the production of elec-


Previous Page

tronic components, mainly tantalum capacitors, which are very small relative to their capacity. Because of this size and weight advantage, major end uses for tantalum capacitors include portable telephones, pagers, personal computers, and automotive electronics.Tantalum is also used to produce a variety of alloys that have high melting points, are

strong and have good ductility. Alloyed with other metals, it is also used in making carbide tools for metalworking equipment and in the production of superalloys for jet engine components, chemical process equipment, nuclear reactors, and missile parts. It is ductile and can be drawn into fine wire, which is used as a filament for evapo-rating metals such as aluminium. Because it is totally immune to the action of body liquids and is nonirritating it is widely used in making surgical appliances. Tantalum oxide is used to make special high refractive index glass for camera lenses. The metal is also used to make vacuum furnace parts.

History

Tantalum (Greek Tantalos, mythological character) was discovered in Sweden in 1802 by Anders Ekeberg and isolated in 1820 by Jons Berzelius. Many contemporary chem-ists believed niobium and tantalum were the same elements until 1844 and later 1866 when researchers showed that niobic and tantalic acids were different compounds. Early investigators were only able to isolate impure metal and the first relatively pure ductile metal was produced by Werner von Bolton in 1903. Wires made with tantalum metal were used for light bulbs until tungsten replaced it.Its name is derived from the character Tantalus, father of Niobe in Greek mythology,

who was punished after death by being condemned to stand knee-deep in water with perfect fruit growing above his head, both of which eternally tantalized him - if he bent to drink the water, it drained below the level he could reach, and if he reached for the fruit, the branches moved out of his grasp. This was considered similar to tan-talum's general non-reactivity - it sits among reagents and is unaffected by them.

Occurrence

Tantalum occurs principally in the mineral tantalite [(Fe, Mn) Ta2O6] and euxenite (other minerals: samarskite, and fergusonite).Tantalum ores are mined in Australia, Brazil, Canada, the Democratic Republic of the

Congo, Mozambique, Nigeria, Portugal, and Thailand. Tantalite is largely found mixed with columbite in an ore called coltan.Several complicated steps are involved in the separation of tantalum from niobium.

Commercially production of this element can follow one of several different methods which includes; electrolysis of molten potassium fluorotantalate, reduction of po-tassium fluorotantalate with sodium, or by reacting tantalum carbide with tantalum oxide. Tantalum is also a byproduct from tin extraction.

Compounds

Los Alamos National Laboratory scientists have made a tantalum carbide graphite composite material that is one of the hardest materials made.

IsotopesNatural tantalum consists of two isotopes. Ta-181 is a stable isotope, and Ta-180 is a ra-

dioactive isotope that quickly transforms into a nuclear isomer with a half life of over a 1015 years (1 with 15 zeros).



Previous Page

TungstenTungsten (formerly Wolfram) is a chemical element in the periodic table that has the

symbol W (L. Wolframium), atomic number 74 and atomic weight of 183.84. It is a Tran-sition Metal.

• Name: Tungsten• Symbol: W• Atomic number: 74• Atomic weight: 183.84• Standard state: solid at 298 K• CAS Registry ID: 7440-33-7• Group in periodic table: 6• Group name: (none)• Period in periodic table: 6• Block in periodic table: d-block• Colour: greyish white, lustrous• Classification: Metallic

A very hard, heavy, steel-gray to white transition metal, tungsten is found in sever-al ores including wolframite and scheelite and is remarkable for its robust physical properties. The pure form is used mainly in electrical applications but its many com-pounds and alloys are widely used in many applications (most notably in light bulb filaments and in space-age superalloys).

Notable CharacteristicsPure tungsten is steel-gray to tin-white and is a hard metal. Tungsten can be cut with

a hacksaw when it is very pure (it is brittle and hard to work when impure) and is oth-erwise worked by forging, drawing, or extruding. This element has the highest melt-ing point (3422°C), lowest vapor pressure and the highest tensile strength at tempera-tures above 1650°C of all metals. Its corrosion resistance is excellent and it can only be attacked slightly by most mineral acids. Tungsten metal forms a protective oxide when exposed to air. When alloyed in small quantities with steel, it greatly increases its hardness.

ApplicationsTungsten is a metal with a wide range of uses, the largest of which is as tungsten car-

bide (W2C, WC) in cemented carbides. Cemented carbides (also called hardmetals) are wear-resistant materials used by the metalworking, mining, petroleum and construc-tion industries. Tungsten is widely used in light bulb and vacuum tube filaments, as

well as electrodes, because it can be drawn into very thin metal wires that have a high melting point.

Other uses; * A high melting point also makes tungsten suitable for space-oriented and high

temperature uses which include electrical, heating, and welding applications. * Hard-ness and density properties make this metal ideal for making heavy metal alloys that are used in armaments, heat sinks, and high-density applications, such as weights and counterweights. * High speed tool steels (Hastelloy ®, Stellite ®) are often alloyed with tungsten,

with tungsten steels containing as much as 18% tungsten. * Superalloys containing this metal are used in turbine blades, tool steels, and

wear-resistant alloy parts and coatings. * Composites are used as a substitute for lead in bullets and shot. * Tungsten chemical compounds are used in catalysts, inorganic pigments, and

tungsten disulfide high-temperature lubricants which is stable to 500°C. * Since this element's thermal expansion is similar to borosilicate glass, it is used for making glass-to-metal seals. * It is used Kinetic energy penetrators as an alternative to depleted uranium

Miscellaneous: Oxides are used in ceramic glazes and calcium/magnesium tungstates are used wide-

ly in fluorescent lighting. The metal is also used in X-ray targets, heating elements for electrical furnaces. Salts that contain tungsten are used in the chemical and tan-ning industries. Tungsten 'bronzes' (so called due to the colour of the tungsten oxides) along with other compounds are used in paints.

HistoryTungsten (Swedish tung sten meaning "heavy stone", even though the current name

for the element in Swedish is Wolfram) was first hypothesized to exist by Peter Woulfe in 1779 who examined wolframite (which was later named for Woulfe) and concluded that it must contain a new substance. In 1781 Carl Wilhelm Scheele ascertained that a new acid could be made from tungstenite. Scheele and Torbern Bergman suggested that it could be possible to obtain a new metal by reducing tungstic acid. In 1783 Josè and Fausto Elhuyar found an acid in wolframite that was identical to tungstic acid. In Spain later that year the brothers succeeded in isolating tungsten through reduction of this acid with charcoal. They are credited with the discovery of the element.

Biological RoleEnzymes called oxidoreductases use tungsten in a way that is similar to molybdenum

by using it in a tungsten-pterin complex.On August 20, 2002 officials representing the U.S.-based Centers for Disease Control

and Prevention announced that urine tests on leukemia patient families and control group families in the Fallon, Nevada area had shown elevated levels of the metal tung-sten in the bodies of both groups. 16 recent cases of cancer in children were discov-ered in the Fallon area which has now been identified as a "Cancer Cluster." Dr. Carol H. Rubin, a branch chief at the CDC, said data demonstrating a link between tungsten and leukemia are not available at present.

Occurrence


Previous Page

Tungsten is found in the minerals wolframite (iron-manganese tungstate, (Fe,Mn)WO4), scheelite (calcium tungstate, (CaWO4), ferberite (FeWO4) and hübnerite (MnWO4). Important deposits of these minerals are in Bolivia, California, China, Col-orado, Portugal, Russia, and South Korea (with China producing about 75% of the world's supply). The metal is commercially produced by reducing tungsten oxide with hydrogen or carbon.

CompoundsThe most common oxidation state of tungsten is +6, but it exhibits all oxidation states

from ?2 to +6. Tungsten typically combines with oxygen to form the yellow tungstic oxide, WO3, which dissolves in aqueous alkaline solutions to form tungstate ions, WO42-.Aqueous polyoxoanionsAqueous tungstate solutions are noted for the formation of polyoxoanions under

neutral and acidic conditions. As tungstate is progressively treated with acid, it first yields the soluble, metastable "paratungstate A" anion, W7O246-, which over hours or days converts to the less soluble "paratungstate B" anion, H2W12O4210-.Further acidification produces the very soluble metatungstate anion, H2W12O406-,

after equilibrium is reached. The metatungstate ion exists as a symmetric cluster of twelve tungsten-oxygen octahedra known as the "Keggin" anion. Many other poly-oxoanions exist as metastable species. The inclusion of a different atom such as phos-phorus in place of the two central hydrogens in metatungstate produces a wide vari-ety of the so-called heteropolyanions.

IsotopesNaturally occurring tungsten consists of five radioisotopes whose half-lives are so

long that for most practical purposes they are considered stable. 27 other radioiso-topes have been characterized, the most stable of which are W-181 with a half-life of 121.2 days, W-185 with a half-life of 75.1 days, W-188 with a half-life of 69.4 days and W-178 with a half-life of 21.6 days.All of the remaining radioactive isotopes have half-lives of less than 24 hours, and

most of these have half-lives that are less than 8 minutes. Tungsten also has 4 meta states, the most stable being W-179m (t1/2 6.4 minutes).The isotopes of tungsten range in atomic weight from 157.974 amu (W-158) to 189.963

amu (W-190). The primary decay mode before the most abundant isotope, W-184, is electron capture, and the primary mode after is beta decay. The primary decay prod-ucts before W-184 are element 73 (tantalum) isotopes, and the primary products after are element 75 (rhenium) isotopes.


RheniumRhenium is a chemical element in the periodic table that has the symbol Re, atomic

number 75 and atomic weight of 186.207. It is a Transition metal element.

• Name: Rhenium• Symbol: Re• Atomic number: 75• Atomic weight: 186.207• Standard state: solid at 298 K• CAS Registry ID: 7440-15-5• Group in periodic table: 7• Group name: (none)• Period in periodic table: 6• Block in periodic table: d-block• Colour: greyish white• Classification: Metallic

A silvery-white, rare, heavy, polyvalent transition metal, rhenium resembles manga-nese chemically and is used in some alloys. Rhenium is obtained as a by-product of molybdenum refinement and rhenium-molybdenum alloys are superconducting. This was the last naturally-occurring element to be discovered.

Notable CharacteristicsRhenium is a silvery white metal, lustrous, and has one of the highest melting points

of all elements, exceeded by only tungsten and carbon. It is also one of the most dense, exceeded only by platinum, iridium, and osmium. The oxidation states of rhe-nium include -1,+1,+2,+3,+4,+5,+6 and +7 oxidation states. The oxidation states +7,+6,+4,+2 and -1 are the most common.Its usual commercial form is a powder, but this element can be consolidated by press-

ing and resistance-sintering in a vacuum or hydrogen atmosphere. This procedure yields a compact shape that is in excess of 90 percent of the density of the metal. When annealed this metal is very ductile and can be bent, coiled, or rolled. Rheni-um-molybdenum alloys are superconductive at 10 K.

ApplicationsThis element is used in platinum-rhenium catalysts which in turn are primarily used

in making lead-free, high-octane gasoline and in high-temperature superalloys that


Previous Page

are used to make jet engine parts.

Other uses: * Widely used as filaments in mass spectrographs and in ion gauges. * An additive to tungsten and molybdenum-based alloys to give them useful proper-

ties. * Rhenium catalysts are very resistant to chemical poisoning, and so are used in cer-

tain kinds of hydrogenation reactions. * Electrical contact material due to its good wear resistance and ability to withstand

arc corrosion. * Thermocouples containing alloys of rhenium and tungsten are used to measure

temperatures up to 2200 Â°C. * Rhenium wire is used in photoflash lamps in photography.

HistoryRhenium (Latin Rhenus meaning "Rhine") was the last naturally-occurring element

to be discovered. It is generally considered to be discovered by Walter Noddack, Ida Tacke, and Otto Berg in Germany. In 1925 they reported that they detected the element in platinum ore and in the mineral columbite. They also found rhenium in gadolinite and molybdenite. In 1928 they were able to extract 1 g of element by processing 660 kg of molybdenite.The process was so complicated and the cost so high that production was discontin-

ued until early 1950 when tungsten-rhenium and molybdenum-rhenium alloys were prepared. These alloys found important applications in industry that resulted in a great demand for the rhenium produced from the molybdenite fraction of porphyry copper ores.

OccurrenceRhenium is not naturally found free in nature or even as a compound in a distinct

mineral species. This element is widely spread through the earth's crust at approxi-mately 0.001 ppm. Commercial rhenium is extracted from molybdenum roaster-flue dusts from copper-sulfide ores. Some molybdenum ores contain 0.002% to 0.2% rheni-um. The metal form is prepared by reducing ammonium perrhentate with hydrogen at high temperatures.

Isotopes

Naturally occurring rhenium is a mix of one stable isotope and one radioactive iso-tope with a very long half-life. There are twenty six other unstable isotopes recog-nized.


OsmiumOsmium is a chemical element in the periodic table that has the symbol Os, atomic

number 76. and atomic weight of 190.23. It is a transition metal. Precious metal ele-ment.

• Name: Osmium• Symbol: Os• Atomic number: 76• Atomic weight: 190.23• Standard state: solid at 298 K• CAS Registry ID: 7440-04-2• Group in periodic table: 8• Group name: Precious metal or Platinum group metal• Period in periodic table: 6• Block in periodic table: d-block• Colour: bluish grey• Classification: Metallic

A hard brittle blue-gray or blue-black transition metal in the platinum family, osmi-um is the densest natural element and is used in some alloys with platinum and irid-ium. Osmium is found native as an alloy in platinum ore and its tetroxide has been used to stain tissues and in fingerprinting. Alloys of osmium are employed in fountain pen tips, electrical contacts and in other applications where extreme durability and hardness are needed.

Notable CharacteristicsOsmium in a metallic form is extremely dense, blue white, brittle and lustrous even at

high temperatures, but proves to be extremely difficult to make. Powdered osmium is easier to make, but powdered osmium exposed to air leads to the formation of osmi-um tetroxide (OsO4), which is toxic. The oxide is also a powerful oxidizing agent, emits a strong smell and boils at 130°C.Due to its very high density osmium is generally considered to be the heaviest known

element narrowly defeating iridium. However, calculations of density from the space lattice may produce more reliable data for these elements than actual measurements and give a density of 22,650 kg/m3 for iridium versus 22,661 kg/m3 for osmium. Defin-itive selection between the two is therefore not possible at this time. It's just too close to call.This metal has the highest melting point and the lowest vapor pressure of the plat-

inum family. Common oxidation states of osmium are +4 and +3, but oxidation states


Previous Page

from +1 to +8 are observed.

ApplicationsBecause of the extreme toxicity of its oxide, osmium is rarely used in its pure state,

and is instead often alloyed with other metals that are used in high wear applications. Osmium alloys are very hard and along with other platinum group metals is almost entirely used in alloys employed in the tips of fountain pens, phonograph needles, instrument pivots, and electrical contacts.Osmium tetroxide has been used in fingerprint detection and in staining fatty tissue

for microscope slides. An alloy of 90% platinum and 10% osmium (90/10) is used in sur-gical implants such as pacemakers and replacement pulmonary valves.The tetroxide (and a related compound, potassium osmate) are important oxidants

for chemical synthesis.

HistoryOsmium (Greek osme meaning "a smell") was discovered in 1803 by Smithson Tennant

in London, England along with iridium in the residue of dissolving platinum in aqua regia.

OccurrenceThis transition metal is found in iridiosmium a naturally occurring alloy of iridium

and osmium and in platinum-bearing river sands in the Ural Mountains, and North and South America. It is also occurs in nickel-bearing ores found in the Sudbury, On-tario region with other platinum group metals. Even though the quantity of platinum metals found in these ores is small, the large volume of nickel ores processed makes commercial recovery possible.

IsotopesOsmium has seven naturally-occurring isotopes, 5 of which are stable: Os-187, Os-188,

Os-189, Os-190, and (most abundant) Os-192. Os-184, Os-186 have absurdly long half lifes and for practical purposes can be consided to be stable as well. Os-187 is the daugh-ter of rhenium-187 (half-life 4.56 x 1010 years) and is most often measured in a Os-187/Os-186 ratio. This ratio, as well as the Re-187/Os-187 ratio, have been used extensively in dating terrestrial as well as meteoric rocks. However, the most notable application of Os in dating has been in conjunction with ridium, to analyze the layer of shocked quartz along the K-T boundary that marks the extinction of the dinosaurs 65 million years ago.


IridiumIridium is a chemical element in the periodic table that has the symbol Ir, atomic

number 77 and atomic weight of 192.217. It is a transition metal Precious metal ele-ment.

• Name: Iridium• Symbol: Ir• Atomic number: 77• Atomic weight: 192.217• Standard state: solid at 298 K• CAS Registry ID: 7439-88-5• Group in periodic table: 9• Group name: Precious metal or Platinum group metal• Period in periodic table: 6• Block in periodic table: d-block• Colour: silvery white• Classification: Metallic

A heavy, very hard, brittle, silvery-white transition metal of the platinum family, irid-ium is used in high strength alloys that can withstand high temperatures and occurs in natural alloys with platinum or osmium. Iridium is notable for being the most cor-rosion resistant element known and for its association with the demise of the dino-saurs. It is used in high temperature apparatus, electrical contacts, and as a hardening agent for platinum.

Notable CharacteristicsA platinum family metal, iridium is white, resembling platinum, but with a slight yel-

lowish cast. Due to its extreme hardness and brittle properties, iridium is difficult to machine, form, or work. Iridium is the most corrosion-resistant metal known.Iridium cannot be attacked by any acids or by aqua regia, but it can be attacked

by molten salts, such as NaCl and NaCN. The specific gravity of this element is only slightly lower than osmium, which is generally considered to be the heaviest element known. However, calculations of density from the space lattice may produce more re-liable data for these elements than actual measurements and give a density of 22650 kg/mÂ³ for iridium versus 22661 kg/mÂ³ for osmium. Definitive selection between the two is therefore not possible at this time.

ApplicationsThe principal use of iridium is as a hardening agent in platinum alloys.


Previous Page

Other uses: * For making crucibles and devices that require high temperatures. * Electrical contacts (notable example: Pt/Ir sparkplugs). * Osmium/iridium alloys are used for tipping fountain pen nibs and for compass

bearings. * Iridium is used as a catalyst for carbonylation of methanol to produce acetic acid

At one time iridium, as an alloy with platinum, was used in bushing the vents of heavy ordnance and, in a finely powdered condition (iridium black), for painting porcelain black.

HistoryIridium (Latin iris meaning "rainbow", "iridium" means "of rainbows") was discovered

in 1803 by Smithson Tennant in London, England along with osmium in the dark col-ored residue of dissolving crude platinum in aqua regia (a mixture of hydrochloric and nitric acid). This element was named after the Latin word for rainbow because its salts are highly colored.This metal was used in the standard metre bar and kilogram mass, kept by the Inter-

national Bureau of Weights and Measures near Paris. These are made of an alloy of 90% platinum and 10% iridium. In 1960 the Paris metre bar was replaced as the defini-tion of the fundamental unit of length (see krypton), but the kilogram mass is still the international standard of mass.The KT event, marking the temporal border between the Cretaceous and Tertiary eras

of geological time, was identified by a thin stratum of iridium-rich clay. According to many scientists, such as Luis Alvarez, this iridium was of extraterrestrial origin, at-tributed to a asteroid or a comet thought to have struck near what is now the Yucatan Peninsula.However, there are others such as Dewey M. McLean of Virginia Polytechnic Institute

who argue that the iridium was of volcanic origin. The Earth's core is rich in iridium, and Piton de la Fournaise on RÃ©union, for example, is still releasing iridium today.

OccurrenceIridium is found uncombined in nature with platinum and other platinum group

metals in alluvial deposits. Naturally occurring iridium alloys include osmiridium and iridiosmium, both of which are mixtures of iridium and osmium. It is recovered com-mercially as a by-product from nickel mining and processing.IsotopesThere are two natural isotopes of iridium, and many radioisotopes, the most stable

being Ir-192 with a half-life of 73.83 days. Ir-192 beta decays into platinum-192, while most of the other radioisotopes decay into osmium.


Platinum

Platinum is a chemical element in the periodic table that has the symbol Pt, atomic number 78 and atomic weight of 195.078. It is a transition metal Precious metal ele-ment.

• Name: Platinum• Symbol: Pt• Atomic number: 78• Atomic weight: 195.078• Standard state: solid at 298 K• CAS Registry ID: 7440-06-4• Group in periodic table: 10• Group name: Precious metal or platinum group metal• Period in periodic table: 6• Block in periodic table: d-block• Colour: greyish white• Classification: Metallic

A heavy, malleable, ductile, precious, gray-white transition metal, platinum is resis-tant to corrosion and occurs in some nickel and copper ores along with some native deposits. Platinum is used in jewelry, laboratory equipment, electrical contacts, den-tistry, and anti-pollution devices in automobiles.


The metal is a beautiful silvery-white when pure, and malleable and ductile. The metal is corrosion-resistant. The catalytic properties of the six platinum family metals are outstanding (a mixture of hydrogen and oxygen explodes in the presence of plati-num). Platinum's wear and tarnish-resistance characteristics are well-suited for mak-ing fine jewelry.Other distinctive properties include resistance to chemical attack, excellent

high-temperature characteristics, and stable electrical properties. All these properties have been exploited for industrial applications. Platinum does not oxidize in air at any temperature but can be corroded by cyanides, halogens, sulfur, and caustic alkalis. This metal is insoluble in hydrochloric and nitric acid but does dissolve when mixed as aqua regia (forming chloroplatinic acid). Common oxidation states of platinum in-clude +2, +3, and +4.


Previous Page

Applications

Platinum is used extensively in jewelry, wire, in making crucibles for chemical use and for constructing high-temperature electric furnaces. Finely divided platinum is often used as a chemical catalyst. For example, platinum is used in catalytic convert-ers for automobiles and in various industrial processes, such as the manufacture of sulfuric acid.

Other uses: * The metal can absorb large quantities of hydrogen gas and will release it when

heated. It is therefore been studied as a possible storage medium for the gas for use in fuel cell vehicles. * The chemical industry uses a significant amount of either platinum or a plati-

num-rhodium alloy catalyst in the form of gauze to catalyze the partial oxidation of ammonia to yield nitric oxide, which is the raw material for fertilizers, explosives, and nitric acid. * Platinum-supported catalysts are used in the refining of crude oil, reforming, and

other processes used in the production of high-octane gasoline and aromatic com-pounds for the petrochemical industry. * This metal has a coefficient of expansion that is almost equal to that of so-

da-lime-silica glass and is therefore used to make sealed electrodes in glass systems. * Alloys of platinum and cobalt have excellent magnetic properties. One alloy that

has 76.7% Pt and 23.3% Co, by mass, forms an extremely powerful magnet. * 90/10 Platinum/osmium alloy is used to make pacemakers, replacement valves and

other surgical implants. * Used for coating missile nose cones, jet engine fuel nozzles, and other devices

which must perform reliably at high temperatures for extended periods of time. * Fine platinum wire glows red hot when exposed to methyl alcohol vapor acting as

a catalyst that converts the alcohol to formaldehyde. This phenomenon has been com-mercially used to make cigarette lighters and hand warmers. * Cis-platin, [PtCl2(NH3)2], is a drug that is effective in treating certain types of can-

cer which include leukemia and testicular cancer.

History

The name platinum derives from the Spanish platina meaning "little silver".Naturally-occurring platinum and platinum-rich alloys have been known for a long

time. Though the metal was used by pre-Columbian Indians, the first European refer-ence to platinum appears in 1557 in the writings of the Italian humanist Julius Caesar Scaliger (1484-1558) as a description of a mysterious metal found in Central American mines between DariÃ©n (Panama) and Mexico ("up until now impossible to melt by any of the Spanish arts"). The Spaniards named the metal "platina," or little silver, when they first encountered it in Colombia. They regarded platinum as an unwanted impurity in the silver they were mining, and often discarded it.Platinum was discovered by astronomer Antonio de Ulloa and Don Jorge Juan y Sant-

acilia (1713-1773), both appointed by King Philip V to join a geographical expedition in Peru that lasted from 1735 to 1745. Among other things, Ulloa observed the platina del pinto, the unworkable metal found with gold in New Granada (Colombia). British pri-vateers intercepted Ulloa's ship on the return voyage. Though he was well-treated in

England, and even made a member of the Royal Society he was prevented from pub-lishing a reference to the unknown metal until 1748. Before that could happen Charles Wood independently isolated the element in 1741. The alchemical symbol for platinum was made by joining the symbols of silver and gold.Platinum is now considered more precious than gold, so that a platinum award is bet-

ter than a golden one. The price of platinum changes along with its availability, but it normally costs about twice as much as gold.The standard definition of a metre for a long time was based on the distance between

two marks on a bar of a platinum-iridium alloy housed at the Bureau International des Poids et Mesures in Sevres, France. A platinum-iridium cylinder serves to this day as the standard of the kilogram and is housed in the same facility as the meter bar. Plati-num is also used in the definition of the Standard hydrogen electrode.

Occurrence

Platinum is often found in a native state and the ore sperrylite (platinum arsenide, PtAs2) is a major source of the metal. A naturally occurring platinum/iridium alloy is platiniridium and this metal is also found in the mineral cooperite (platinum sulfide, PtS).This metal is often accompanied by small amounts of other platinum family metals

which are found in alluvial deposits in Colombia, Ontario, the Ural Mountains, and in certain western American states.Platinum is produced commercially as a by-product of nickel ore processing. The

huge quantities of nickel ore processed makes up for the fact that platinum makes up only two parts per million of the ore.

Isotopes

Naturally occurring platinum is composed of five stable isotopes and one radioiso-tope, Pt-190, which has a very long half-life (over 6 billion years). There are also many other radioisotopes with the most stable being Pt-193 with a half-life of 50 years.



Previous Page

Gold

Gold is a chemical element in the periodic table that has the symbol Au (L. aurum), atomic number 79 and atomic weight of 196.966569. It is a transition metal Precious metal element.

• Name: Gold• Symbol: Au• Atomic number: 79• Atomic weight: 196.966569• Standard state: solid at 298 K• CAS Registry ID: 7440-57-5• Group in periodic table: 11• Group name: Coinage metal• Period in periodic table: 6• Block in periodic table: d-block• Colour: gold• Classification: Metallic

A soft, shiny, yellow, heavy, malleable, ductile (trivalent and univalent) transition metal, gold does not react with most chemicals but is attacked by chlorine, fluorine, and aqua regia. The metal occurs as nuggets or grains in rocks and in alluvial deposits and is one of the coinage metals.Gold is used as a monetary standard for many nations and is also used in jewelry,

dentistry, and in electronics. Its ISO currency code is XAU.


Gold is a metallic element that exhibits a yellow color en masse but can be black, ruby, or purple when finely divided. It is the most malleable and ductile metal known. In fact, 1 gram can be beaten into a 1 meter squared sheet, or 1 ounce into 300 feet squared. A soft metal, gold is often alloyed with other metals to give it more strength.Gold is also a good conductor of heat and electricity and is not affected by air and

most reagents. It is quite chemically unalterable by heat, moisture, and most corrosive agents and therefore is well suited for its use in coin and jewelry.The color of solid gold as well as of the intensely colored, often purple, colloidal solu-

tions that can be made from it is caused by the fact that the plasmon frequency of this element lies in the visible range, which causes red and yellow light to be reflected and blue light to be absorbed. Native gold contains usually eight to ten per cent silver, but

often much more. Natural alloys with a high silver content are called electrum. As the amount of silver increases, the color becomes whiter and the specific gravity lower.Gold will alloy with many other metals, alloys with copper yield a redder metal, alloys

with iron are green, aluminium alloys are purple, alloys with platinum metals produce white, natural bismuth with silver alloys produce black. Jewelry made with combina-tions of colored gold is sold in the western United States to the tourist trade as Black Hills gold. Common oxidation states of gold include +1 and +3.

Applications

Pure gold is too soft for ordinary use and is hardened by alloying with silver and copper. Gold and its many alloys are most often used in jewelry, coinage and as a standard for monetary exchange in many countries. Because of its superior electrical conductivity and resistance to corrosion and other desirable combinations of physical and chemical properties, gold also emerged in the late 20th century as an essential industrial metal.

Other uses: * Gold performs critical functions in computers, communications equipment, space-

craft, jet aircraft engines, and a host of other products. * The high electrical conductivity and resistance to oxidation of gold has led to its

widespread use as thin layers electroplated on the surface of electrical connectors to ensure a good, low-resistance connection. * Like silver, gold can form a hard amalgam with mercury, and is sometimes used for

dental fillings. * Colloidal gold (gold nanoparticles) is an intensely colored solution that is currently

studied in many labs for medical, biological and other applications. It is also the form used as gold paint on ceramics prior to firing. * Chlorauric acid is used in photography for toning the silver image. * Disodium aurothiomalate is a treatment for rheumatoid arthritis (administered

intramuscularly). * The gold isotope Au-198, (half-life: 2.7 days) is used in some cancer treatments and

for treating other diseases. * Gold is used as a coating enabling biological material to be viewed under a scan-

ning electron microscope. * Many competitions and honors, such as the Olympics and the Nobel Prize, award a

gold medal to the winner (with silver to the second-place finisher, and bronze to the third.) * Since it is a good reflector of both infrared and visible light, it is used for the pro-

tective coatings on many artificial satellites. * Gold flake is used on and in some gourmet sweets and drinks. Having no reactivity

it adds no taste but is taken as a delicacy.

History

Gold has been known and highly valued since prehistoric times. Egyptian hieroglyphs from 2600 BC describe gold, which the Mesopotamian king Tushratta referred to as being "common as dust" in Egypt. Egypt and Nubia had the resources to make them major gold-producing areas for much of history. Gold is also mentioned several times


Previous Page

in the Old Testament. The south-east corner of the Black Sea was famed for its gold. Exploitation is said to date from the time of Midas, and this gold was important in the establishment of what is probably the world's earliest coinage in Lydia in 700BC.The European exploration of the Americas was fueled in no small part by reports of

the gold ornaments displayed in great profusion by Native American peoples, espe-cially in Central America, Peru, and Colombia.Gold has long been considered one of the most precious metals, and its value has

been used as the standard for many currencies (known as the gold standard) in his-tory. Gold has been used as a symbol for purity, value, royalty, and particularly roles that combine these properties (see gold album).Gold in antiquity was relatively easy to obtain geologically however 75% of all gold

ever produced has been extracted since 1910 (see Goldsheet, cumulative gold produc-tion (http://www.goldsheetlinks.com/production2.htm)). It has been estimated that all the gold in the world that has ever been refined would form a single cube 20 m (66 ft) a side.

Alchemy

The primary goal of the alchemists was to produce gold from other substances, such as lead, presumably by the interaction with a mythical substance called the philoso-pher's stone. Although they never succeeded in this attempt, the alchemists promoted an interest in what can be done with substances, and this laid a foundation for today's chemistry. Their symbol for gold was the circle with a point at its center, which was also the astrological symbol, the Egyptian hieroglyph and the ancient Chinese charac-ter for the Sun.ValueLike other precious metals, gold is measured by troy weight and by grams and when

it is alloyed with other metals the term carat is used to indicate the amount of gold present, with 24 carats being pure gold. The purity of a gold bar can also be expressed as a decimal figure, known as the millesimal fineness, such as 0.995.The price of gold is determined on the open market, but a procedure known as the

Gold Fixing in London, originating in 1919, provides a twice-daily benchmark figure to the industryHistorically gold was used to back currency in an economic system known as the gold

standard in which one unit of currency was equivalent to a certain amount of gold. As part of this system, governments and central banks attempted to control the price of gold by setting values at which they would exchange it for currency. For a long peri-od the United States government set the price of gold at $20.67 per troy ounce but in 1934 the price of gold was set at $35.00 per troy ounce. By 1961 it was becoming hard to maintain this price, and a pool of US and European banks began to act together to defend the price against market forces.On March 17, 1968, economic circumstances caused the collapse of the gold pool, and

a two-tiered pricing scheme was established whereby gold was still used to settle international accounts at the old $35.00 per troy ounce ($1.13/g) but the price of gold on the private market was allowed to fluctuate; this two-tiered pricing system was abandoned in 1975 when the price of gold was left to find its free-market level. Cen-tral banks still hold historical gold reserves as a reserve asset although the level has generally been declining. The largest gold depository in the world is the U.S. Federal Reserve Bank.

Since 1968 the price of gold on the open market has ranged widely, with a record high of $850 on 21 January 1980, to a low of $252.90 on 21 June 1999 (London Fixing). Prices have risen to the $420 mark in 2004, part of this rise was associated with a depreci-ation of the US dollar (an inverse relation between the prices exsists to a certain ex-tent).Because of its use as a reserve store of value, the possession of gold is sometimes

restricted or banned. Within the United States, the private possession of gold except as jewelry and coin collecting was banned between 1933 and 1975. President Franklin D. Roosevelt confiscated gold by Executive Order 6102, and President Richard Nixon closed the gold window by which foreign countries could exchange American dollars for gold at a fixed rate.As a tangible investment gold is sometimes held as part of a portfolio because over

the long term gold has an extensive history of maintaining its value. It has in the last century however lost ground to inflation. Thus the only way to make money over the long term on gold investing in normal economic conditions is to trade it, attempt-ing to buy low and sell high. This carries large amounts of risk and transaction costs. However, gold does become particularly desirable in times of extremely weak confi-dence and during hyperinflation because gold maintains its value even as fiat money becomes worthless. People who despite the risks enjoy investing in gold are known as goldbugs.Futures contracts based on gold currently trade on the COMEX (Commodity Ex-

change) which is a subsidiary of the New York Mercantile Exchange. Speculation about the future price of gold and other commodities are carried on here.

Occurrence

Due to its relative chemical inertness gold is usually found as the native metal some-times as large nuggets, but usually as minute grains in minerals, typically quartz (usually as veins), or sulfide minerals most commonly, pyrite, chalcopyrite, galena, sphalerite, arsenopyrite, stibnite and pyrrhotite or associated with these minerals. Gold more rarely occurs with tellurium in the minerals petzite, calaverite, sylvanite, muthmannite, nagyagite and krennerite.Gold is widely distributed in the earth's crust at a background level of 0.03 g/1000 kg

(0.03 ppm), hydrothermal ore deposits of gold occur in metamorphic rocks and igne-ous rocks, alluvial deposits and placer deposits originate from these sources.The primary source of gold is usually igneous rocks or surface concentrations. A de-

posit usually needs some form of secondary enrichment to form an economically via-ble ore deposit: either chemical or physical processes like erosion or solution or more generally metamorphism, which concentrates the gold in sulfide minerals or quartz. There are several primary deposit types, common ones are termed reef or vein. Pri-mary deposits can be weathered and eroded, with most of the gold being transported into stream beds where it congregates with other heavy minerals to form placer de-posits. In all these deposits the gold is in its native form. Another important ore type is in sedimentary black shale deposits containing finely disseminated gold and other platinum group metals.Gold ore grades may be as little as 0.5 g/1000 kg (0.5 ppm) on average in large easily

mined deposits, typical ore grades in open-pit mines are 1 - 5 g/1000 kg (1-5 ppm), ore grades in underground or hard rock mines are usually at least 3 g/1000 kg (3 ppm) on average. Ore grades of 30 g/1000 kg (30 ppm) are usually needed before gold will be


Previous Page

visible to the naked eye, therefore even in gold mines you will often not see any gold.Gold is extracted from alluvium ores by techniques of placer mining and from hard

rock ores by initially crushing and grinding the ore and then by one or more of the following techniques; gravity separation, flotation, cyanidation, amalgamation, roast-ing, bioleaching or pressure oxidation(autoclaving). Refining of the metal is frequent-ly accomplished by electrolysis. Gold occurs in sea water at 0.1 to 2 mg/1000 kg (0.1 - 2 ppb) depending on sample location. However, as of 2004 there is no profitable method for recovering gold from sea water.Since the 1880s South Africa has been the source for about two-thirds of the world's

gold supply. The city of Johannesburg was built atop the world's greatest gold finds. Gold fields in the Orange Free State and the Transvaal were deep and require the world's deepest mines. The Boer War of 1899 - 1901 between the British and the white Boers was at least partly over the rights of miners and possession of the gold wealth in South Africa. Other major producers are Canada, United States and Western Austra-lia. Mines in South Dakota and Nevada supply two-thirds of gold used in the United States.

Compounds

Auric chloride (AuCl3) and chlorauric acid (HAuCl4) are the most common compounds of gold. Although gold is a noble metal it can form many compounds. * It dissolves in Aqua regia to form the AuCl4- ion * Gold halides (F,Cl,Br,I) * Gold chalcogenides (O, S, Se,Te) * Gold cluster compounds.

Isotopes

There is only one stable isotope of gold, and 18 radioisotopes with Au-195 being the most stable with a half-life of 186 days.


Mercury

Mercury also called quicksilver, is a chemical element in the periodic table that has the symbol Hg (L. hydrargyrum) and atomic number 80, and Atomic weight of 200.59. It is a Metallic element.

• Name: Mercury• Symbol: Hg• Atomic number: 80• Atomic weight: 200.59• Standard state: liquid at 298 K (the heaviest known elemental liquid)• CAS Registry ID: 7439-97-6• Group in periodic table: 12• Group name: (none)• Period in periodic table: 6• Block in periodic table: d-block• Colour: silvery white• Classification: Metallic

A heavy, silvery, transition metal, mercury is one of only two elements that are liquid at room temperature (the other is bromine). Mercury is used in thermometers, barom-eters and other scientific apparatuses. Mercury is mostly obtained by reduction from the mineral cinnabar.


Mercury is a relatively poor conductor of heat but is a good conductor of electricity.Mercury easily forms alloys with almost all common metals, including gold and silver

but not iron. Tellurium forms an alloy also, but it reacts slowly to form mercury tellu-ride. The reaction of mercury with sulfur is more easily noticed. Any of these alloys is called an amalgam.This metal also has uniform volumetric thermal expansion, is less reactive than zinc

and cadmium and does not displace hydrogen from acids. Common oxidation states of this element are +1 and +2. Rare instances of +3 mercury compounds exist. The com-mercial unit for handling mercury is the "flask," which weighs 76 lb.

Applications


Previous Page

Most mercury is used for the manufacture of industrial chemicals or for electrical and electronic applications. Mercury is also used in thermometers, especially ones which are used to measure high temperatures. Other uses: * The ease with which it forms amalgams with gold has resulted in its use in gold

recovery from ores. * In addition to thermometers, mercury is used in barometers, diffusion pumps, and

many other laboratory instruments. * The triple point of mercury, -38.8344 Â°C, is a fixed point used as a temperature

standard for the International Temperature Scale (ITS-90). * Gaseous mercury is used in mercury-vapor lamps and advertising signs. * Mercury compounds are used as a preservative in vaccines and tattoo inks. Miscel-

laneous uses; mercury switches, pesticides, dental amalgams/preparations, mercury cells for sodium hydroxide and chlorine production, anti-fouling paint, electrodes in some types of electrolysis, batteries (mercury cells), and catalysts.

History

Mercury was known to the ancient Chinese and Hindus and was found in Egyptian tombs that date from 1500s BC. By 500 BC it was used to make amalgams with oth-er metals. The ancient Greeks used mercury in ointments and the Romans used it in cosmetics. Alchemists thought it to be the stuff from which all matter was formed and they also thought that when it hardened it turned into gold.In the 18th and 19th centuries, mercury nitrate was used to remove fur from the an-

imal skins from which felt hats were made. This caused many cases of brain damage among hatters, or milliners, leading, it is claimed, to the simile "as mad as a hatter", and thereby to the Mad Hatter of Alice in Wonderland fame.It was named by alchemists after the Roman god Mercury. Its symbol Hg comes from

hydrargyrum, a Latinised form of the Greek word hydrargyros, which was a compound word whose Greek roots meant 'water' and 'silver'. Mercury is one of the few elements that has an alchemical symbol (left).

Occurrence

A rare element in the earth's crust, mercury is found either as a native metal (rare) or in cinnabar, corderoite, livingstonite, and other minerals with cinnabar (HgS) be-ing the most common ore. Approximately 50% of the global supply comes from Spain and Italy, with much of the rest coming from Slovenia, Russia, and North America. The metal is extracted by heating cinnabar in a current of air and condensing the vapor.

Compounds

The most important salts are: * Mercury (I) chloride (AKA calomel and is sometimes still used in medicine) * Mercury (II) chloride (which is very corrosive, sublimates and is a violent poison) * Mercury fulminate, (a detonator widely used in explosives), and * Mercury (II) sulfide (AKA vermilion which is a high-grade paint pigment). Organic

mercury compounds are also important. Laboratory test have found that electrical discharge causes the noble gases to combine with mercury vapor. These compounds

are held together with van der Waals forces and result in HgNe, HgAr, HgKr, and HgXe. Methyl mercury is a dangerous compound that is widely found as a pollutant in water bodies and streams.

Isotopes

There are seven stable isotopes of mercury with Hg-202 being the most abundant (26.86%). The longest-lived radioisotopes are Hg-194 with a half-life of 444 years, and Hg-203 with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lifes that are less than a day.



Previous Page

Thallium

Thallium is the chemical element in the periodic table that has the symbol Tl, atomic number 81 and atomic weight of 204.3833. It is a Metallic element.

• Name: Thallium• Symbol: Tl• Atomic number: 81• Atomic weight: 204.3833• Standard state: solid at 298 K• CAS Registry ID: 7440-28-0• Group in periodic table: 13• Group name: (none)• Period in periodic table: 6• Block in periodic table: p-block• Colour: silvery white• Classification: Metallic

This soft gray malleable poor metal resembles tin but discolors when exposed to air. Thallium is highly toxic and is used in rodent and insect poisons but since it can also cause cancer, this use has been cut back or eliminated in many countries. It is also used in infrared detectors.


This metal is very soft and malleable and can be cut with a knife. When it is first ex-posed to air, thallium has a metallic luster but quickly tarnishes with a bluish-gray tinge that resembles lead (it is preserved by keeping it under water). A heavy layer of oxide builds up on thallium if left in air, and in the presence of water thallium hydride is formed.

Applications

The odorless and tasteless thallium sulfate was widely used in the past as a rat poi-son and ant killer. In the United States and many other countries, this use is no longer allowed due to safety concerns.

Other uses:

* Thallium sulfide's electrical conductivity changes with exposure to infrared light therefore making this compound useful in photocells. * Thallium bromide-iodide crystals have been used as infrared optical materials. * Tthallium oxide has been used to manufacture glasses that have a high index of

refraction. * Used in semiconductor materials for selenium rectifiers. * In gamma radiation detection equipment. * High-density liquid used for sink-float separation of minerals. * Used in the treatment of ringworm and other skin infections. However this use has

been limited due to the narrow margin that exists between toxicity and therapeutic benefit. * Radioactive thallium-201 is used for diagnostic purposes in nuclear medicine, par-

ticularly in stress tests used for risk stratification in patients with coronary artery disease (CAD). * Combined with sulfur or selenium and arsenic, thallium has been used in the pro-

duction of high-density glasses that have low melting points in the range of 125 and 150°C. These glasses have room temperature properties that are similar to ordinary glasses and are durable, insoluble in water and have unique refractive indexes.In addition, research activity with thallium is ongoing to develop high-temperature

superconducting materials for such applications as magnetic resonance imaging, storage of magnetic energy, magnetic propulsion, and electric power generation and transmission.

History

Thallium (Greek thallos meaning "a green shoot or twig") was discovered by Sir Wil-liam Crookes in 1861 in England while he was making spectroscopic determinations for tellurium on residues from a sulfuric acid plant. The name comes from Thallium's bright green spectral emission lines. In 1862 Crookes and Claude-Auguste Lamy isolat-ed the metal independent of each other.

Occurrence

Although the metal is reasonably abundant in the Earth's crust at a concentration estimated to be about 0.7 part per million, it exists mostly in association with potas-sium minerals in clays, soils, and granites and, thus, is not generally considered to be commercially recoverable from those forms. The major source of commercial thallium is the trace amounts found in copper, lead, zinc, and other sulfide ores.Thallium is found in the minerals crooksite, hutchinsonite, and lorandite. This met-

al is also contained in pyrites and is extracted as a by-product of sulfuric acid pro-duction when pyrite ore is roasted. Another way this element is obtained is from the smelting of lead and zinc rich ores. Manganese nodules which are found on the ocean floor, also contain thallium but nodule extraction is prohibitively expensive and po-tentially environmentally destructive. In addition, several other thallium minerals containing 16% to 60% thallium, occur in nature as sulfide or selenide complexes with antimony, arsenic, copper, lead, and silver but are rare and have no commercial im-portance as sources of this element.


Previous Page

Isotopes

Thallium has 25 isotopes which have atomic masses that range from 184 to 210. Tl - 203 and Tl - 205 are the only stable isotopes and Tl - 204 is the most stable radioiso-tope with a half-life of 3.78 years.


Lead

Lead is a chemical element in the periodic table that has the symbol Pb, atomic num-ber 82 and atomic weight of 207.2. It is a Metallic element.

• Name: Lead• Symbol: Pb• Atomic number: 82• Atomic weight: 207.2• Standard state: solid at 298 K• CAS Registry ID: 7439-92-1• Group in periodic table: 14• Group name: (none)• Period in periodic table: 6• Block in periodic table: p-block• Colour: bluish white• Classification: Metallic

A soft, heavy, toxic and malleable poor metal, lead has a dull gray appearance and is bluish white when freshly cut but tarnishes to dull gray when exposed to air. Lead is used in building construction, lead-acid accumulators, bullets and shot, and is part of solder, pewter, and fusible alloys. Lead has the highest atomic number of all stable elements.


Lead has a bright luster and is a ductile, very soft, highly malleable, bluish-white met-al that has poor electrical conductivity. This true metal is highly resistant to corro-sion. Because of this property, it is used to contain corrosive liquids (e.g. sulfuric acid). Lead can be toughened by adding a small amount of antimony or other metals to it.

Applications

Early uses of lead included building materials, pigments for glazing ceramics, and pipes for transporting water. The castles and cathedrals of Europe contain consider-able quantities of lead in decorative fixtures, roofs, pipes, and windows. Lead is the fifth most widely used metal (in its elemental state) after iron, aluminium, copper and zinc.


Previous Page

Common uses include: * Lead-acid batteries, in electronic components, cable sheathing, ammunition, in the

glass of CRTs, ceramics, leaded glass (see glass making), lead piping (not much used these days, although leaded solder was legal for use on drinking water pipes into the 1980s (US)), in paint (banned since 1978 in the US, and gradually in the UK from the 1950s to the 1970s, although older painted surfaces could be up to 50% lead by weight), casting alloys, pewter, solder, and dentistry filling. Also used as flashing on roofing to protect joins from rain. In gasoline (petrol) as tetra-ethyl lead and tetra-methyl lead to reduce knocking (also called pre-detonation, pre-ignition or pinking) from the 1920s, in 1986 leaded gasoline was banned from sale in the United States, in the EU in 1999. Lead is a superconductor with critical temperature Tc=7.20 K (-265.95°C).

History

Lead has been used by humans for at least 7000 years, because it was (and continues to be) widespread and easy to extract, as well as easy to work with, being both high-ly malleable and ductile as well as easy to smelt. Lead was mentioned in the Book of Exodus. Alchemists thought that lead was the oldest metal and associated it with the planet Saturn. Lead pipes that bear the insignia of Roman emperors are still in service and many Roman "pigs" (ingots) of lead figure in Derbyshire lead mining history and in the history of the industry in other English centres. Lead's symbol Pb is an abbrevi-ation of its Latin name plumbum. The English word "plumbing" also derives from this Latin root.By the mid-1980s, a significant shift in lead end-use patterns had taken place. Much

of this shift was a result of the U.S. lead consumers' compliance with environmental regulations that significantly reduced or eliminated the use of lead in nonbattery products, including gasoline, paints, solders, and water systems.

Extraction

Native lead does occur in nature, but it is rare. Currently lead is usually found in ore with zinc, silver and (most abundantly) copper, and is extracted together with these metals. The main lead mineral is galena (PbS), which contains 86.6% lead. Other com-mon varieties are cerussite (PbCO3) and anglesite (PbSO4). But more than half of the lead used currently comes from recycling.In mining, the ore is extracted by drilling or blasting and then crushed and ground.

The ore is then taken through a process developed in the 19th century at Broken Hill, Australia. A flotation process separates the lead and other minerals from the waste rock (tailings) to form a concentrate by passing the ore, water and certain chemicals through a series of tanks in which the slurry is constantly mixed. Air is blown through the tanks and lead sulfides attach to the bubbles and rise to form a foam which can be removed. The foam (which is around 50% lead) is dried and then sintered before being smelted to produce a 97% lead concentrate. The lead is then cooled in stages which causes the lighter impurites (dross) to rise to the surface where they can be removed. The molten lead bullion is then refined by additional smelting with air being passed over the lead to form a slag layer containing any remaining impurities and producing 99.9% pure lead.

Isotopes

Lead has four stable, naturally occurring isotopes: Pb-204 (1.4%), Pb-206 (24.1%), Pb-207 (22.1%) and Pb-208 (52.4%). Pb-206, Pb-207 and Pb-208 are all radiogenic, and are the end products of complex decay chains that begin at U-238, U-235 and Th-232 re-spectively. The corresponding half-lives of these decay schemes vary markedly: 4.47 * 109, 7.04 * 108 and 1.4 *1010 years, respectively. Each is reported relative to 204Pb, the only non-radiogenic stable isotope. The ranges of isotopic ratios for most natural materials are 14.0-30.0 for Pb-206/Pb-204, 15.0-17.0 for Pb-207/Pb-204 and 35.0-50.0 for Pb-208/Pb-204, although numerous examples outside these ranges are reported in the literature.



Previous Page

BismuthBismuth is a chemical element in the periodic table that has the symbol Bi, atomic

number 83 and atomic weight of 208.9804 and it is a Prnctogen, a Metallic element.

• Name: Bismuth• Symbol: Bi• Atomic number: 83• Atomic weight: 208.98040• Standard state: solid at 298 K• CAS Registry ID: 7440-69-9• Group in periodic table: 15• Group name: Pnictogen• Period in periodic table: 6• Block in periodic table: p-block• Colour: lustrous reddish white• Classification: Metallic

This heavy, brittle, white crystalline trivalent poor metal has a pink tinge and chemi-cally resembles arsenic and antimony. Most diamagnetic of all metals, bismuth has the lowest thermal conductivity of all the elements except mercury. Lead-free bismuth compounds are used in cosmetics and in medical procedures.

Notable CharacteristicsIt is a brittle metal with a pinkish hue with an iridescent tarnish. Among the heavy

metals, it is the heaviest and the only non-toxic. No other metal is more diamagnetic than bismuth, except mercury. This metal, which occurs in its native form, has a high electrical resistance and also has the highest Hall effect of any metal (that is, it has the greatest increase in electrical resistance when it is placed in a magnetic field). When heated in air bismuth burns with a blue flame and its oxide forms yellow fumes.Bismuth has long been thought to be unstable on theoretical grounds, but not until

2003 was this demonstrated when researchers at the Institut d'Astrophysique Spa-tiale in Orsay, France measured the alpha emission half-life of Bi-209, meaning that bismuth is not truly stable, though in effect it is. Due to this phenomenal half-life, the use of bismuth in (eg) certain medicines poses no radiological hazard. Any food con-taining the normal amount of carbon 14 is many thousands of times more radioactive than bismuth. However, the radioactivity was of academic interest because bismuth is one of few elements whose radioactivity was suspected, and indeed theoretically predicted, rather than detected in the lab. An immortal who lost a digestive bacterium

every year, or a hair every several thousand years, would lose mass more rapidly than a sample of bismuth decays.

ApplicationsBismuth oxychloride is extensively used in cosmetics and bismuth subnitrate and

subcarbonate are used in medicine. Bismuth subsalicylate is a bright pink liquid used as an antidiarrheal.

Some other uses are: Strong permanent magnets can be made from the alloy bismanol (MnBi). Many bis-

muth alloys have low melting points and are widely used for fire detection and sup-pression system safety devices. Bismuth is used in producing malleable irons. Bismuth is finding use as a catalyst for making acrylic fibers. Also used as a thermocouple ma-terial. A carrier for U-235 or U-233 fuel in nuclear reactors.Bismuth has also been used in solders. The fact that bismuth and many of its alloys

expand slightly when they freeze make them ideal for this purpose. Bismuth subni-trate is a component of glazes that produces an iridescent luster finish.In the early 1990s, research began on the evaluation of bismuth as a nontoxic replace-

ment for lead in such uses as ceramic glazes, fishing sinkers, food processing equip-ment, free-machining brasses for plumbing applications, lubricating greases, and shot for waterfowl hunting.

CrystalsThough virtually unseen in nature, high-purity bismuth can form into distinctive

hopper crystals. These colorful laboratory creations are typically sold to hobbyistsHistoryBismuth (New Latin bisemutum from German Wismuth, perhaps from weisse Masse,

"white mass") was confused in early times with tin and lead due to its resemblance to those elements. Claude Geoffroy Junine showed in 1753 that this metal is distinct from lead.

OccurrenceThe most important ores of bismuth are bismuthinite and bismite. Canada, Bolivia,

Japan, Mexico, and Peru are major producers. Bismuth produced in the United States is obtained as a by-product of copper, gold, lead, silver, tin and especially lead ore processing. The average price for bismuth in 2000 was US$ 7.70 per kilogram.



Previous Page

Polonium

Polonium is a chemical element in the periodic table that has the symbol Po, atomic number 84 and atomic weight of 209. It is a metalloid element.in the Chalcogen group .

• Name: Polonium• Symbol: Po• Atomic number: 84• Atomic weight: 209• Standard state: solid at 298 K• CAS Registry ID: 7440-08-6• Group in periodic table: 16• Group name: Chalcogen• Period in periodic table: 6• Block in periodic table: p-block• Colour: silvery• Classification: Metallic

A rare radioactive metalloid, polonium is chemically similar to tellurium and bismuth and occurs in uranium ores. Polonium had been studied for possible use in heating spacecraft.


This radioactive substance dissolves readily in dilute acids, but is only slightly soluble in alkalis. It is closely related chemically to bismuth and tellurium.Polonium-210 is a volatile metal with 50% being vaporized in air after 45 hours at 328

K. This isotope is an alpha emitter that has a half-life of 138.39 days. A milligram of this metalloid emits as many alpha particles as 5 grams of radium. A single gram of Poloni-um-210 generates 140 watts of heat energy.A great deal of energy is released by its decay with a half a gram quickly reaching a

temperature above 750 K. A few curies of polonium emit a blue glow which is caused by excitation of surrounding air.

ApplicationsWhen it is mixed or alloyed with beryllium, polonium can be a neutron source.

Other uses:

* This element has also been used in devices that eliminate static charges in textile mills and other places. However beta sources are more commonly used and are less dangerous. * Polonium is used on brushes that remove accumulated dust from photographic

films. The polonium in these brushes is sealed and controlled thus minimizing radia-tion hazards. * Polonium is used as thermoelectric power in space satellitesSince nearly all alpha radiation can be easily stopped by ordinary containers and

upon hitting its surface releases its energy, polonium has been proposed as a light-weight heat source to power thermoelectric cells in artificial satellites.

HistoryAlso called Radium F, Polonium was discovered by Marie Curie and Pierre Curie in

1898 and was later named after Marie's home land of Poland. Poland at the time was under Russian domination, and not recognized as a nation. It was Marie's hope that naming the element after her home land would add noteriety to it's plight. Polonium may be the first element named to highlight a political controversy.This element was the first one discovered by the Curies while they were investigat-

ing the cause of pitchblende radioactivity. The pitchblende, after removal of uranium and radium, was more radioactive than both radium and uranium put together. This spurred them on to find the element. The electroscope showed it separating from bis-muth.

OccurrenceA very rare element in nature, polonium is found in uranium ores at about 100 micro-

grams per ton. Its natural abundance is approximately 0.2% of radium's.In 1934 an experiment showed that when natural bismuth (Bi-209) is bombarded with

neutrons, Bi-210, which is the parent of polonium, was created. Polonium may now be made in milligram amounts in this procedure which uses high neutron fluxes found in nuclear reactors.

IsotopesPolonium has many isotopes all of which are radioactive. There are 25 known iso-

topes of polonium with atomic masses that range from 194 to 218. Polonium-210 is the most widely available. Po-209 (half-life 103 years) and Po-208 (half-life 2.9 years) can be made through the alpha, proton, or deuteron bombardment of lead or bismuth in a cyclotron. However these isotopes are expensive to produce.



Previous Page

Astatine

Astatine is a chemical element in the periodic table that has the symbol At, atom-ic number 85 and atomic weight of 210. It is a Semi-metallic element in the Halogen group.

• Name: Astatine• Symbol: At• Atomic number: 85• Atomic weight: 210• Standard state: solid at 298 K• CAS Registry ID: 7440-68-8• Group in periodic table: 17• Group name: Halogen• Period in periodic table: 6• Block in periodic table: p-block• Colour: metallic• Classification: Semi-metallic

This radioactive element occurs naturally from uranium and thorium decay and is the heaviest of the halogens.


This highly radioactive element has been confirmed by mass spectrometers to be-have chemically much like other halogens, especially iodine (it probably accumulates in the thyroid gland like iodine). Astatine is thought to be more metallic than iodine. Researchers at the Brookhaven National Laboratory have performed experiments that have identified and measured elementary reactions that involve astatine. The total amount of astatine in Earth's crust is estimated to be less than 1 oz (28 g) at any one time. This amounts to less than one teaspoon of the element.

History

Astatine (Greek astatos meaning "unstable") was first synthesized in 1940 by Dale R. Corson, K. R. MacKenzie, and Emilio Segre of the University of California, Berkeley by barraging bismuth with alpha particles.

Occurrence

Astatine is produced by bombarding bismuth with energetic alpha particles to obtain relatively long-lived At-209 - At-211, which can then be distilled from the target by heating in the presence of air.

Isotopes

Astatine has about 20 known isotopes, all of which are radioactive; the longest-lived isotope is 210At which has a half-life of only 8.3 hours



Previous Page

Radon

Radon is a chemical element in the periodic table that has the symbol Rn, atomic number 86 and atomic weight of 222. It is a Noble gas.

• Name: Radon• Symbol: Rn• Atomic number: 86• Atomic weight: 222• Standard state: gas at 298 K (the heaviest known mononuclear gas at

298 K)• CAS Registry ID: 10043-92-2• Group in periodic table: 18• Group name: Noble gas• Period in periodic table: 6• Block in periodic table: p-block• Colour: colourless• Classification: Non-metallic

A radioactive noble gas that is formed by the disintegration of radium, radon is one of the heaviest gases and is considered to be a health hazard. The most stable isotope is Rn-222 which has a half-life of 3.8 days and is used in radiotherapy.


Essentially inert, radon is the heaviest noble gas and one of the heaviest gases at room temperature. (The heaviest is tungsten hexafluoride, WF6.) At standard tem-perature and pressure radon is a colorless gas but when it is cooled below its freezing point it has a brilliant phosphorescence which turns yellow as the temperature is low-ered and orange-red at the temperature air liquefies. Some experiments indicate that fluorine can react with radon and form radon fluoride. Radon clathrates have also been reported.Natural radon concentrations in Earth's atmosphere are so low that natural waters

in contact with the atmosphere will continually lose radon by volatilization. Hence, ground water has a higher concentration of Rn-222 than surface water. Likewise, the saturated zone of a soil frequently has a higher radon content than the unsaturated zone due to diffusional losses to the atmosphere.

Applications

Radon is sometimes produced by a few hospitals for therapeutic use by pumping its gas from a radium source and storing it in very small tubes which are called seeds or needles. This practice is being phased-out as hospitals get seeds from suppliers who make them with the desired activity levels. Such seeds - often using radioactive forms of cobalt and caesium - also last for several years, which is a logistical advantage.Because of its rapid loss to air, radon is used in hydrologic research that studies the

interaction between ground water, streams and rivers. Any significant concentration of radon in a stream or river is a good indicator that there are local inputs of ground water.

History

Radon (named for radium) was discovered in 1900 by Friedrich Ernst Dorn, who called it radium emanation. In 1908 William Ramsay and Robert Whytlaw-Gray, who named it niton (Latin nitens meaning "shining"; symbol Nt), isolated it, determined its density and that it was the heaviest known gas. It has been called radon since 1923.

Occurrence

On average, there is one molecule of radon in 1 x 1021 molecules of air. Soil down to depth of 6 inches (150 mm) has about 1 gram of radium, which decays to radon and releases tiny amounts of this deadly gas into the atmosphere. Radon can be found in some spring waters and hot springs. The town of Misasa, Japan, boasts its radium-rich springs exhausting radon.Radon exhausts naturally from the ground, particularly in certain regions, especial-

ly but not only regions with granitic soils. Not all granitic regions are prone to high exhausts of radon. Depending on how houses are built and ventilated, radon may accumulate in basements and dwellings. The European Union recommends that action should be taken starting from concentrations of 4003 for old houses, and 2003 for new ones. The United States Environmental Protection Agency recommends action for any house with a conectration higher then 4In SI uints, the US standard is 1483. Nearly one in 15 homes in the U.S. has a high level of indoor radon. The U.S. Surgeon General and EPA recommend all homes be tested for radon. Since 1985, millions of homes have been tested for radon in the U.S.In most cases, simply increased ventilation suffices in reducing the danger. Other

measures, such as blocking fissures and vents through which radon reaches from the ground, may have to be taken. A layer of foil under the carpet or floor helps block the radon gas from rising up into the house. About 1.2 million new homes have been built with radon-resistant features since 1990 in the U.S. To date, EPA estimates that as many as 650 future lung cancer deaths are prevented (lives saved) each year as a re-sult of houses altered and new houses built with preventative features installed.

Isotopes

There are twenty known isotopes of radon. The most stable isotope is radon-222 which is a decay product (daughter isotope) of radium-226, has a half-life of 3.823 days


Previous Page

and emits radioactive alpha particles. Radon-220 is a natural decay product of tho-rium and is called thoron. It has a half-life of 55.6 seconds and also emits alpha rays. Radon-219 is derived from actinium, is called actinon, is an alpha emitter and has a half-life of 3.96 seconds.


Actinium

Actinium is a chemical element in the periodic table that has the symbol Ac, atomic number 89 ang atomic weight of 227. It is a Actinoid.

• Name: Actinium• Symbol: Ac• Atomic number: 89• Atomic weight: 227• Standard state: solid at 298 K• CAS Registry ID: 7440-34-8• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: silvery• Classification: Metallic


Actinium is a silvery radioactive metallic element. Due to its intense radioactivity, Actinium glows in the dark with an eerie blue light. It is found only in traces in urani-um ores as 227-Ac, an â and â emitter with a half-life of 21.773 years. One ton of urani-um ore contains about a tenth of a gram of actinium.

Applications

It is about 150 times as radioactive as radium, making it valuable as a neutron source. Otherwise it has no significant industrial applications. Actinium-225 is used in med-icine to produce Bi-213 in a reusable generator or can be used alone as an agent for radio-immunotherapy.

History

Actinium was discovered in 1899 by AndrÃ©-Louis Debierne, a French chemist, who separated it from pitchblende. Friedrich Otto Giesel independently discovered ac-tinium in 1902. The chemical behavior of actinium is similar to that of the rare earth lanthanum. The word actinium comes from the Greek aktis, aktinos, meaning beam or


Previous Page

ray.

Occurrence

Actinium is found in trace amounts in uranium ore, but more commonly is made in milligram amounts by the neutron irradiation of 226-Ra in a nuclear reactor. Actinium metal has been prepared by the reduction of actinium fluoride with lithium vapor at about 1100 to 1300°C.

Isotopes

Naturally occurring actinium is composed of 1 radioactive isotope; with 227-Ac being the most abundant (100% natural abundance). 27 radioisotopes have been character-ized with the most stable being 227-Ac with a half-life of 21.773 years, 225-Ac with a half-life of 10 days, and 226-Ac with a half-life of 29.37 hours. All of the remaining ra-dioactive isotopes have half-lifes that are less than 10 hours and the majority of these have half lifes that are less than 1 minute. This element also has 2 meta states. Purified actinium-227 comes into equilibrium with its decay products at the end of 185 days, and then decays according to its 21.773-year half-life. The isotopes of actinium range in atomic weight from 206 u (206-actinium) to 234 u (234-actinium).


Thorium

Thorium is a chemical element in the periodic table that has the symbol Th, atomic number 90 and atomic weight of 232.03806. It is a Actinoid.

• Name: Thorium• Symbol: Th• Atomic number: 90• Atomic weight: 232.03806• Standard state: solid at 298 K• CAS Registry ID: 7440-29-1• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic• Notable characteristics

Thorium is a naturally occurring, slightly radioactive metal. When pure, thorium is a silvery white metal that retains its lustre for several months. However, when it is con-taminated with the oxide, thorium slowly tarnishes in air, becoming grey and even-tually black. Thorium oxide (ThO2), also called thoria, has one of the highest boiling points of all oxides (3300°C). When heated in air, thorium metal turnings ignite and burn brilliantly with a white light.

Applications

Applications of thorium:* Mantles in portable gas lights. These mantles glow with a dazzling light when

heated in a gas flame. * As an alloying element in magnesium, imparting high strength and creep resis-

tance at elevated temperatures. * Thorium is used to coat tungsten wire used in electronic equipment. * Thorium

has been used in welding electrodes and heat-resistant ceramics. * The oxide is used to control the grain size of tungsten used for electric lamps. * The oxide is used for high-temperature laboratory crucibles. * Thorium oxide added to glass helps create glasses of a high refactive index and


Previous Page

with low dispersion. Consequently, they find application in high quality lenses for cameras and scientific instruments. * Thorium oxide has been used as a catalyst: - In the conversion of ammonia to nitric acid. - In petroleum cracking. - In producing sulfuric acid. * Uranium-thorium age dating has been used to date hominid fossils. * As a fertile material for producing nuclear fuel. * Thorium dioxide (ThO2) is the active ingredient of Thorotrast, which was used as

part of X-ray diagnostics. This use has been abandoned due to the carcinogenic na-ture of Thorotrast.

History

Thorium was discovered in 1828 by the Swedish chemist Jöns Jacob Berzelius, who named it after Thor, the Norse god of war. The metal had virtually no uses until the invention of the lantern mantle in 1885.

Occurrence

Thorium is found in small amounts in most rocks and soils, where it is about three times more abundant than uranium, and is about as common as lead. Soil commonly contains an average of around 6 parts per million (ppm) of thorium.Thorium occurs in several minerals, the most common being the rare earth-thori-

um-phosphate mineral, monazite, which contains up to about 12% thorium oxide. There are substantial deposits in several countries. Thorium-232 decays very slowly (its half-life is about three times the age of the earth) but other thorium isotopes oc-cur in the thorium and uranium decay chains. Most of these are short-lived and hence much more radioactive than Th-232, though on a mass basis they are negligible.

Thorium as a Nuclear Fuel

Thorium, as well as uranium, can be used as fuel in a nuclear reactor. Although not fissile itself, thorium-232 (Th-232) will absorb slow neutrons to produce uranium-233 (U-233), which is fissile. Hence, like uranium-238 (U-238), it is fertile.In one significant respect U-233 is better than uranium-235 and plutonium-239, be-

cause of its higher neutron yield per neutron absorbed. Given a start with some other fissile material (U-235 or Pu-239), a breeding cycle similar to but more efficient than that with U-238 and plutonium (in slow-neutron reactors) can be set up. The Th-232 absorbs a neutron to become Th-233 which normally decays to protactinium-233 and then U-233. The irradiated fuel can then be unloaded from the reactor, the U-233 sep-arated from the thorium, and fed back into another reactor as part of a closed fuel cycle.Problems include the high cost of fuel fabrication due partly to the high radioactivity

of U-233 which is always contaminated with traces of U-232; the similar problems in recycling thorium due to highly radioactive Th-228, some weapons proliferation risk of U-233; and the technical problems (not yet satisfactorily solved) in reprocessing. Much development work is still required before the thorium fuel cycle can be com-

mercialised, and the effort required seems unlikely while (or where) abundant urani-um is available.Nevertheless, the thorium fuel cycle, with its potential for breeding fuel without the

need for fast neutron reactors, holds considerable potential long-term. Thorium is significantly more abundant than uranium, so it is a key factor in the sustainability of nuclear energy.India has particularly large reserves of thorium, and so have planned their nuclear

power program to eventually use it exclusively, phasing out uranium as an input ma-terial. This ambitious plan uses both fast and thermal breeder reactors.

Isotopes

Naturally occurring thorium is composed of 1 isotope: 232-Th. 25 radioisotopes have been characterized with the most {abundant and/or stable} being 232-Th with a half-life of 14.05 billion years, 230-Th with a half-life of 75,380 years, 229-Th with a half-life of 7340 years, and 228-Th with a half-life of 1.92 years. All of the remaining radioactive isotopes have half-lifes that are less than 30 days and the majority of these have half lifes that are less than 10 minutes. This element also has 1 meta state. The isotopes of thorium range in atomic weight from 212 amu (212-Th) to 236 amu (236-Th).



Previous Page

Protactinium

Protactinium is a chemical element in the periodic table that has the symbol Pa, atomic number 91 and atomic weight of 231.03588. It is a Metallic Actinoid.

• Name: Protactinium• Symbol: Pa• Atomic number: 91• Atomic weight: 231.03588• Standard state: solid at 298 K• CAS Registry ID: 7440-13-3• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: silvery metallic• Classification: Metallic


Protactinium is a silver metallic element that belongs to the actinide group, with a bright metallic luster that it retains for some time in the air. It is superconductive at temperatures below 1.4 K.

Applications

Due to its scarcity, high radioactivity and toxicity, there are currently no uses for protactinium outside of basic scientific research.

History

Protactinium was first identified in 1913, when Kasimir Fajans and O. H. Göhring en-countered short-lived isotope 234m-Pa, with a half-life of about 1.17 minutes, during their studies of the decay chain of 238-U. They gave the new element the name Brevi-um (Latin brevis, brief, short); the name was changed to Protoactinium in 1918 when two groups of scientists (Otto Hahn and Lise Meitner of Germany and Frederick Soddy and John Cranston of the UK) independently discovered 231-Pa, and shortened to Prot-actinium in 1949.

Aristid V. Grosse prepared 2 mg of Pa2O5 in 1927, and later on managed to isolate Protactinium for the first time in 1934 from 0.1 mg of Pa2O5, first converting the oxide to an iodide and then cracking it in a high vacuum by an electrically heated filament by the reaction 2PaI5 ? 2Pa + 5I2.In 1961, the United Kingdom Atomic Energy Authority was able to produce 125 g of

99.9% pure protactinium, processing 60 tons of waste material in a 12-stage process and spending 500,000 USD; this was the world's only supply of the element for many years to come, and it is reported that the metal was sold to laboratories for a cost of 2,800 USD / g in the following years.Biological RoleProtactinium does not play any biological role.

Occurrence

Protactinium occurs in pitchblende to the extent of about 1 part 231-Pa to 10 million of ore; ores from Zaire have about 3 ppm.

Isotopes

29 radioisotopes of protactinium have been characterized, with the most stable being 231-Pa with a half life of 32760 years, 233-Pa with a half-life of 26.967 days, and 230-Pa with a half-life of 17.4 days. All of the remaining radioactive isotopes have half-lifes that are less than 1.6 days, and the majority of these have half lifes that are less than 1.8 seconds. This element also has 2 meta states, 217m-Pa (t1/2 1.15 milliseconds) and 234m-Pa (t1/2 1.7 minutes).The primary decay mode before the most stable isotope, 231-Pa, is alpha decay and

the primary mode after is beta minus decay. The primary decay products before 231-Pa are element Ac (actinium) isotopes and the primary products after are element U (uranium) isotopes.



Previous Page

Uranium

Uranium is a chemical element in the periodic table that has the symbol U, atomic number 92 and atomic weight of 238.02891. It is a Actinoid.

• Name: Uranium• Symbol: U• Atomic number: 92• Atomic weight: 238.02891• Standard state: solid at 298 K• CAS Registry ID: 7440-61-1• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: metallic grey• Classification: Metallic

A heavy, silvery-white, toxic, metallic , and naturally-radioactive element, urani-um belongs to the actinide series and its isotope uranium-235 is used as the fuel for nuclear reactors and nuclear weapons. Uranium is commonly found in very small amounts in rocks, soil, water, plants, and animals (including humans).

Notable CharacteristicsWhen refined, uranium is a silvery white, weakly radioactive metal, which is slightly

softer than steel. It is malleable, ductile, and slightly paramagnetic. Uranium metal has very high density, 65% more dense than lead. When finely divided, it can react with cold water; in air, uranium metal becomes coated with uranium oxide. Urani-um in ores can be extracted and chemically converted into uranium dioxide or other chemical forms usable in industry.

Uranium metal has three allotropic forms: * alpha (orthorhombic) stable up to 667.7°C * beta (tetragonal) stable from 667.7 °C

to 774.8°C * gamma (body-centered cubic) from 774.8°C to melting point - this is the most

malleable and ductile state. Its two principal isotopes are 235U and 238U (see Urani-um-235 and Uranium-238). Naturally-occurring Uranium also contains a small amount of the 234U isotope, which is a decay product of 238U. The isotope 235U is important for both nuclear reactors and nuclear weapons because it is the only isotope existing

in nature to any appreciable extent that is fissile, that is, fissionable by thermal neu-trons. The isotope 238U is also important because it absorbs neutrons to produce a radioactive isotope that subsequently decays to the isotope 239Pu (plutonium), which also is fissile.The artificial 233U isotope is also fissile and is made from 232thorium by neutron

bombardment.Uranium was the first element that was found to be fissile, i.e. upon bombardment

with slow neutrons, its 235U isotope becomes the very short lived 236U, that imme-diately divides into two smaller nuclei, liberating energy and more neutrons. If these neutrons are absorbed by other 235U nuclei, a nuclear chain reaction occurs, and if there is nothing to absorb some neutrons and slow the reaction, it is explosive.The first atomic bomb worked by this principle (nuclear fission). A more accurate

name for both this and the hydrogen bomb (nuclear fusion) would be "nuclear weap-on", because only the nuclei participate.

ApplicationsUranium metal is very dense and heavy. Depleted uranium (almost pure U-238 with

less than 0.2% U-235) is used by some militaries as shielding to protect tanks, and also in parts of bullets and missiles, as it is extremely dense. The military also uses en-riched uranium (more than natural levels of U-235) to power nuclear propelled navy ships and submarines, and in nuclear weapons. Fuel used for United States Navy reac-tors is typically highly enriched in U-235 (the exact values are classified information). In nuclear weapons uranium is also highly enriched, usually over 90% (again, the exact values are classified information).The main use of uranium in the civilian sector is to fuel commercial nuclear power

plants, where fuel is typically enriched in U-235 to 2-3%. However, the Canadian Candu reactors use natural unenriched uranium as fuel. Depleted uranium is used in helicop-ters and airplanes as counterweights on certain wing parts.

Other uses include:* Ceramic glazes where small amounts of natural uranium (that is, not having gone

through the enrichment process) may be added for color. * Addition of uranium makes fluorescent yellow or green colored glass. * The long

half-life of the isotope uranium-238 (4.51 * 109) make it well-suited for use in estimat-ing the age of the earliest igneous rocks. * U-238 is converted into plutonium in breeder reactors. Plutonium can be used in

reactors, or in nuclear weapons. * Uranyl acetate, UO2(CH3COO)2 is used in analytical chemistry. It forms an insoluble

salt with sodium. * Some lighting fixtures utilize uranium, as do some photographic chemicals (esp. uranium nitrate). * Phosphate fertilizers often contain high amounts of natural uranium, because the

mineral material from which they are made is typically high in uranium. * Uranium metal is used for X-ray targets in making of high-energy X-rays. * The element has found use in inertial guidance devices and in gyroscopic compass-

es.

HistoryThe use of uranium, in its natural oxide form, dates back to at least 79 AD, when it


Previous Page

was used to add a yellow color to ceramic glazes (yellow glass with 1% uranium oxide was found near Naples, Italy).The discovery of the element is credited to the German chemist Martin Heinrich Kl-

aproth who in 1789 found uranium as part of the mineral called pitchblende. It was named after the planet Uranus, which had been discovered eight years earlier. It was first isolated as a metal in 1841 by Eugene-Melchior Peligot. Uranium was found to be radioactive by French physicist Henri Becquerel in 1896, who first discovered the pro-cess of radioactivity with uranium minerals.During the Manhattan Project, the wartime Allied program to develop the first atom-

ic bombs during World War II, uranium gained new importance on the world political scene. Before the discovery of plutonium, only uranium was considered for the de-velopment of an atomic bomb, though the process of enriching it to applicable levels required gargantuan facilities (see Oak Ridge National Laboratory). Eventually enough uranium was enriched for one atomic bomb, which was dropped on Hiroshima, Japan in 1945. The other nuclear weapons developed during the war used plutonium as their fissionable material, which itself requires uranium to produce. Initially it was believed that uranium was relatively rare, though within a decade large deposits of it were dis-covered in many places around the world.The exploration and mining of radioactive ores in the United States began around

the turn of the 20th century. Sources for radium (contained in uranium ore) were sought for use as luminous paint for watch dials and other instruments, as well as for health-related applications (some of which in retrospect were incredibly unhealthy). Because of the need for the element during World War II, the Manhattan Project con-tracted with numerous vanadium mining companies in the American Southwest, and also purchased uranium ore from the Belgian Congo.American uranium ores mined in Colorado were primarily mixes of vanadium and

uranium, but because of wartime secrecy the Manhattan Project would only publicly admit to purchasing the vanadium, and did not pay the uranium miners for the ura-nium ore (in a much later lawsuit, many miners were able to reclaim lost profits from the U.S. government). American uranium ores did not have nearly as high uranium concentrations as the ore from the Belgian Congo, but they were pursued vigorous-ly to ensure nuclear self-sufficiency. Similar efforts were undertaken in the Soviet Union, which did not have native stocks of uranium when it started developing its own weapons program.In the beginning of the Cold War, to ensure adequate supplies of uranium for nation-

al defense, Congress passed the U.S. Atomic Energy Act of 1946, creating the Atomic Energy Commission (AEC) which had the power to withdraw prospective uranium mining land from public purchase, and also to manipulate the price of uranium to meet national needs. By setting a high price for uranium ore, the AEC created a ura-nium "boom" in the early 1950s, which attracted many prospectors to the four corners region of the country. Moab, Utah became the Uranium-capital of the world, when geologist Charles Steen discovered such an ore in 1952.Military requirements declined in the 1960s, and the government completed its

uranium procurement program by the end of 1970. Simultaneously, a new market emerged - commercial nuclear power plants.Because uranium ores emit radon gas, and their harmful and highly radioactive

daughter products, uranium mining is significantly more dangerous than other (al-ready dangerous) hard rock mining, requiring adequate ventilation systems if the mines are not open pit. During the 1950s, a significant amount of American uranium miners were Navajo Indians, as many uranium deposits were discovered on Navajo

reservations. An unusually high number of these miners later developed lung cancer. Some survivors and their descendants received compensation under the Radiation Exposure Compensation Act in 1990.During the Manhattan Project, the names tuballoy and oralloy were used to refer to

natural uranium and enriched uranium respectively, originally for purposes of secre-cy. These names are still used occasionally to refer to natural or enriched uranium.

CompoundsUranium tetrafluoride (UF4) is known as "green salt" and is an intermediate product

in the production of uranium hexafluoride. Uranium hexafluoride (UF6) is a white solid which forms a vapor at temperatures above 56 degrees Celsius. UF6 is the com-pound of uranium used for the two most common enrichment processes, gaseous dif-fusion enrichment and centrifuge enrichment. It is simply called "hex" in the industry.Yellowcake is uranium concentrate. It takes its name from the color and texture of

the concentrates produced by early mining operations, despite the fact that modern mills using higher calcining temperatures produce "yellowcake" that is dull green to almost black. Yellowcake typically contains 70 to 90 percent uranium oxide (U3O8) by weight.Ammonium diuranate is an intermediate product in the production of yellowcake,

and is bright yellow in colour. It is sometimes confusingly called "yellowcake" as well, but this is not a standard name.

OccurrenceUranium is a naturally-occurring element found at low levels in virtually all rock, soil,

and water. It is considered to be more plentiful than antimony, beryllium, cadmium, gold, mercury, silver, or tungsten and is about as abundant as arsenic or molybdenum. It is found in many minerals including pitchblende, uraninite (most common uranium ore), autunite, uranophane, torbernite, and coffinite.Significant concentrations of uranium occur in some substances such as phosphate

rock deposits, and minerals such as lignite, and monazite sands in uranium-rich ores (it is recovered commercially from these sources). Because uranium has such a long radioactive half-life (4.47x109 years for U-238), the total amount of it on Earth stays almost the same.The decay of uranium and its nuclear reactions with thorium in the Earth's core is

thought to be the source for much of the heat that keeps the outer core liquid, which in turn drives plate tectonics. Uranium ore is rock containing uranium mineralization in concentrations that can be mined economically, typically 1 to 4 pounds of uranium oxide per ton or 0.05 to 0.20 percent uranium oxide.

Production and DistributionCommercial-grade uranium can be produced through the reduction of uranium ha-

lides with alkali or alkaline earth metals. Uranium metal can also be made through electrolysis of KUF5 or UF4, dissolved in a molten CaCl2 and NaCl. Very pure uranium can be produced through the thermal decomposition of uranium halides on a hot fila-ment.Owners and operators of U.S. civilian nuclear power reactors purchased from U.S. and

foreign suppliers a total of 21,300 tons of uranium deliveries during 2001. The aver-


Previous Page

age price paid was $26.39 per kilogram of uranium, a decrease of 16 percent compared with the 1998 price. In year 2001, the U.S. produced 1,018 tons of uranium from 7 min-ing operations, all of which are west of the Mississippi River.Uranium is distributed worldwide, especially by the French. Generally, large coun-

tries produce more uranium than smaller ones because the worldwide distribution of uranium is very roughly uniform. Canada is the world's largest producer of uranium, with the world's richest deposits in Saskatchewan. Saskatchewan through three large mines produces over a quarter of the world's uranium. Because of this production, extra capacity, and the close government control of the industry the provincial gov-ernment plays a central role in setting international uranium prices. Australia also has extensive uranium deposits making up approximately 30% of the world's known ura-nium reserves.

IsotopesNaturally occurring uranium is composed of 3 major isotopes, U-238, U-235, and

U-234, with U-238 being the most abundant (99.3% natural abundance). These 3 iso-topes are radioactive, creating radioisotopes, with the most abundant and stable being U-238 with a half-life of 4.5 Ã— 109 years, U-235 with a half-life of 7 Ã— 108 years, and U-234 with a half-life of 2.5 Ã— 105 years.Uranium isotopes can be separated to increase the concentration of one isotope rel-

ative to another. This process is called "enrichment" (see enriched uranium). To be considered to be 'enriched' the U-235 fraction has to be increased to significantly greater than the 0.711% (by weight) (eg typically to levels from 3% to 7%). Uranium-235 is typically the main fissile material for nuclear power reactors. Either U235 or Pu239 are used for making nuclear weapons. The process produces huge quantities of urani-um that is depleted of U-235 and with a correspondingly increased fraction of U-238, called depleted uranium or "DU". To be considered to be 'depleted', the U-235 isotope concentration has to have been decreased to significantly less than 0.711% (by weight). Typically the amount of U235 left in depleted uranium is 0.2% to 0.3%. This represents anywhere from 28% to 42% of the original fraction of U235.Given that the half life of U235 is considerably shorter than U238, the "depleted" ura-

nium is still significantly radioactive as is the natural uranium after refining.Another way to look at this is as follows: Candu style reactors burn natural uranium

(0.71% fissile material). From a PWR reactors of typical design (most USA reactors are PWR) we note the fuel goes in with about 4% U235 and 96% U238 and comes out with about 1% U235, 1% PU239 and 95%U238. If the PU239 were removed (fuel reprocessing is not allowed in the USA) and this were added to the "depleted uranium" then we would have 1.2% fissile material in the reprocessed "depleted uranium" and at the same time have 1% fissile material in the left over "spent" fuel. Both of these would be considered "enriched" fuels for a CANDU style reactor.


Neptunium

Neptunium is a synthetic element in the periodic table that has the symbol Np. atom-ic number 93 and atomic weight of 237.0482. It is a Actinoid .

• Name: Neptunium• Symbol: Np• Atomic number: 93• Atomic weight: 237.0482• Standard state: solid at 298 K• CAS Registry ID: 7439-99-8• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: silvery metallic• Classification: Metallic

A silvery radioactive metallic element, neptunium is the first transuranic ele-ment and belongs to the actinide series. Its most stable isotope, neptunium-237 is a by-product of nuclear reactors and plutonium production and it can be used as a com-ponent in neutron detection equipment. Neptunium is also found in trace amounts in uranium ores.


Silvery in appearance, neptunium metal is fairly chemically reactive and is found in at least three structural modifications: * alpha-neptunium, orthorhombic, density 20,250 kg/m3, * beta-neptunium (above 280°C), tetragonal, density (313 °C) 19,360 kg/m3, and * gamma-neptunium (above 577°C), cubic, density (600°C) 18,000 kg/m3. This element has four ionic oxidation states while in solution: * Np+3 (pale purple), analogous to the rare earth ion Pm+3, *Np+4 (yellow green); * NpO2+ (green blue): and * NpO2++ (pale pink). Neptunium forms tri- and tetrahalides such as NpF3, NpF4,

NpCl4, NpBr3, NpI3, and oxides of the various compositions such as are found in the uranium-oxygen system, including Np3O8 and NpO2.


Previous Page

History

Neptunium (named for the planet Neptune) was first discovered by Edwin McMillan and Philip Abelson in 1940. The discovery was made at the Berkeley Radiation Labora-tory of the University of California, Berkeley where the team produced the neptunium isotope Np-239 (2.4 day half-life) by bombarding uranium with cyclotron-accelerated neutrons. It was the first transuranium element produced synthetically and the first actinide series transuranium element discovered.

Occurrence

Trace amounts of neptunium are found naturally as decay products from trans-mutation reactions in uranium ores. Np-237 is produced through the reduction of NpF3 with barium or lithium vapor at around 1200 Â° C and is most often extracted from spent nuclear fuel rods as a by-product in plutonium production.

Isotopes

19 neptunium radioisotopes have been characterized, with the most stable being Np-237 with a half-life of 2.14 million years, Np-236 with a half-life of 154,000 years, and Np-235 with a half-life of 396.1 days. All of the remaining radioactive isotopes have half-lifes that are less than 4.5 days, and the majority of these have half lifes that are less than 50 minutes. This element also has 4 meta states, with the most stable being Np-236m (t1/2 22.5 hours).The isotopes of neptunium range in atomic weight from 225.0339 u (Np-225) to

244.068 u (Np-244). The primary decay mode before the most stable isotope, Np-237, is electron capture (with a good deal of alpha emission), and the primary mode after is beta emission. The primary decay products before Np-237 are element 92 (uranium) isotopes (alpha emission produces element 91, protactinium, however) and the prima-ry products after are element 93 (plutonium) isotopes.

Weapons ApplicationsIn September, 2002, researchers for the University of California conducting research

for a United States of America weapons of mass destruction development program created the first nuclear critical mass using neptunium rather than plutonium or uranium. US officials in March, 2004, planned to move the nation's supply of enriched neptunium to a site in Nevada.


Plutonium

Plutonium is a radioactive, metallic, chemical element. It has the symbol Pu, atomic number 94 and atomic weight of 244.06. It is a Metallic Actinoid.

• Name: Plutonium• Symbol: Pu• Atomic number: 94• Atomic weight: 244• Standard state: solid at 298 K• CAS Registry ID: 7440-07-5• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic

Plutonium density 19,800 kg/m3. It is the element used in most modern nuclear weapons. The most important isotope of plutonium is 239Pu, with a half-life of 24,200 years.


Plutonium is silvery in pure form, but has a yellow tarnish when oxidized. The heat given off by alpha particle emission makes plutonium warm to the touch in reason-able quantities; larger amounts can boil water. It displays four ionic oxidation states in aqueous solution: * Pu3+ (blue lavender) * Pu4+ (yellow brown) * PuO2+ (pink orange) * PuO+ (thought to be pink; this ion is unstable in solution and will disproportionate

into Pu4+ and PuO2+; the Pu4+ will then oxidize the remaining PuO+ to PuO2+, being reduced in turn to Pu3+. Thus, aqueous solutions of plutonium tend over time towards a mixture of Pu3+ and PuO2+.)

Applications

Plutonium is a key fissile component in modern nuclear weapons, due to its ease of


Previous Page

fissioning and availability. The critical mass for an unreflected sphere of plutonium is 16 kg, but through the use of a neutron reflecting tamper the pit of plutonium in a fission bomb is reduced to 10 kg, which is a sphere with a diameter of 10 cm. Complete detonation of plutonium will produce an explosion of 20 kiloton per kilogram..Plutonium could also be used to manufacture radiological weapons or as a (not par-

ticularly deadly) poison.The plutonium isotope 238Pu is an alpha emitter with a half life of 87 years. These

characteristics make it well suited for electrical power generation for devices which must function without direct maintenance for timescales approximating a human life time. It is therefore used in RTGs such as those powering the Galileo and Cassini space probes; earlier versions of the same technology powered seismic experiments on the Apollo Moon missions.Plutonium 238Pu has been used successfully to power artificial heart pacemakers, to

reduce the risk of repeated surgery. It has been largely replaced by lithium-based bat-teries, but as of 2003 there were somewhere between 50 and 100 plutonium-powered pacemakers still implanted and functioning in living patients.

History

Plutonium was discovered in 1940 by Dr. Glenn T. Seaborg, Edwin M. McMillan, J. W. Kennedy, and A. C. Wahl by deuteron bombardment of uranium in the 60-inch cyclo-tron of the Berkeley Radiation Laboratory at the University of California, Berkeley, but the discovery was kept secret. It was named after the planet Pluto, having been discovered directly after neptunium (which itself was one higher on the periodic table than uranium), by analogy with the ordering of the planets in the solar system. During the Manhattan Project, large reactors were set up in Hanford, Washington for the pro-duction of plutonium, which was used in two of the first atomic bombs (the first was tested at Trinity site, the second dropped on Nagasaki, Japan).Large stockpiles of plutonium were built up by both the old Soviet Union and the

United States during the Cold War, It was estimated that 300,000 kg of plutonium had been accumulated by 1982. Since the end of the Cold War, these stockpiles have be-come a focus of nuclear proliferation concerns. In 2002, the United States Department of Energy took possession of 34 metric tons of excess weapons grade plutonium stock-piles from the United States Department of Defense, and as of early 2003 was consid-ering converting several nuclear power plants in the US from enriched uranium fuel to MOX fuel as a means of disposing of these.

Occurrence

While almost all plutonium is manufactured synthetically, extremely tiny trace amounts are found naturally in uranium ores. These come about by a process of neu-tron capture by 238U nuclei, initially forming 239U; two subsequent beta decays then form 239Pu (with a 239Np intermediary), which has a half-life of 24,100 years. This is also the process used to manufacture 239Pu in nuclear reactors.

Compounds

Plutonium reacts readily with oxygen, forming PuO and PuO2, as well as intermediate

oxides. It reacts with the halides, giving rise to compounds such as PuX3 where X can be F, Cl, Br or I; PuF4 is also seen. The following oxyhalides are observed: PuOCl, PuOBr and PuOI. It will react with carbon to form PuC, nitrogen to form PuN and silicon to form PuSi2.

Isotopes and Synthesis

Twenty radioactive isotopes of plutonium have been characterized. The longest-lived are plutonium-244, with a half-life of 80.8 million years, plutonium-242, with a half-life of 373,300 years, and plutonium-239, with a half-life of 24,110 years. All of the re-maining radioactive isotopes have half-lives that are less than 7,000 years. This ele-ment also has eight metastable states, though none are stable and all have half-lives less than one second.



Previous Page

Americium

Americium is a synthetic element in the periodic table that has the symbol Am, and atomic number 95 and atomic weight 243. It is a Actinoid.

• Name: Americium• Symbol: Am• Atomic number: 95• Atomic weight: 243• Standard state: solid at 298 K• CAS Registry ID: 7440-35-9• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: silvery white• Classification: Metallic

A radioactive metallic element, americium is an actinide that was obtained by bom-barding plutonium with neutrons and was the fourth transuranic element to be dis-covered. It was named for the Americas, by analogy with europium. Notable charac-teristics Freshly prepared americium metal has a white and silvery luster (more silvery than plutonium or neptunium) and at room temperatures it slowly tarnishes in dry air. Alpha emission from Am-241 is approximately three times radium. Gram quantities of Am-241 emit intense gamma rays which creates a serious exposure problem for any-one handling the element.

Applications

This element can be produced in kilogram amounts and has some uses (mostly Am-241 since it is easier to produce relatively pure samples of this isotope). Americium has found its way into the household, where one type of smoke detector contains a tiny amount of Am-241 as a source of ionizing radiation. Am-241 has been used as a porta-ble gamma ray source for use in radiography. The element has also been employed to gauge glass thickness to help create flat glass. Am-242 is a neutron emitter and has found uses in neutron radiography. However this isotope is extremely expensive to produce in usable quantities.

History

Americium was first synthesized by Glenn T. Seaborg, Leon O. Morgan, Ralph A. James, and Albert Ghiorso in late 1944 at the wartime Metallurgical Laboratory at the University of Chicago (now known as Argonne National Laboratory). The team created the isotope Am-241 by subjecting plutonium-239 to successive neutron capture reac-tions in a nuclear reactor. This created Pu-240 and then Pu-241 which in turn decayed into Am-241 via beta decay.

Isotopes

18 radioisotopes of americium have been characterized, with the most stable being Am-243 with a half-life of 7370 years and Am-241 with a half-life of 432.2 years. All of the remaining radioactive isotopes have half-lifes that are less than 51 hours, and the majority of these have half lifes that are less than 100 minutes. This element also has 8 meta states, with the most stable being Am-242m (t1/2 141 years). The isotopes of amer-icium range in atomic weight from 231.046 amu(Am-231) to 249.078 amu (Am-249).



Previous Page

Curium

Curium is a synthetic element in the periodic table that has the symbol Cm, atomic number 96 and atomic weight of 247. It is a Actinoid.

• Name: Curium• Symbol: Cm• Atomic number: 96• Atomic weight: 247• Standard state: solid at 298 K• CAS Registry ID: 7440-51-9• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: silver• Classification: Metallic

A radioactive metallic transuranic element of the actinide series, curium is produced by bombarding plutonium with alpha particles (helium ions) and was named for Marie Curie and her husband Pierre.


The isotope curium-248 has been synthesized only in milligram quantities, but curi-um-242 and curium-244 are made in multigram amounts, which allows for the deter-mination of some of the element's properties. Curium-244 can be made in quantity by subjecting plutonium to neutron bombardment. Very small amounts of curium may exist in uranium ore as a daughter product of natural decay. There are few commer-cial applications for curium but it may one day be useful in radioisotope thermoelec-tric generators. Curium bio-accumulates in bone tissue where its radiation destroys bone marrow and thus stops red blood cell creation.A rare earth homolog, curium is somewhat chemically similar to gadolinium but with

a more complex crystal structure. Chemically reactive, its metal is silvery-white in color and the element is more electropositive than aluminium (most trivalent curium compounds are slightly yellow). Curium-242 is useful as a portable energy source due to the fact that it can generate around 2 watts of thermal energy per gram. It is used in pacemakers, remote navigational buoys, and in space missions.Several curium compounds have been produced. They include: curium dioxide

(CmO2), curium trioxide (Cm2O3), curium bromide (CmBr3), curium chloride (CmCl3), curium tetrafluoride (CmF4) and curium iodide (CmI3).

History

Curium was first synthesized at the University of California, Berkeley and by Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso in 1944. The team named the new element after Marie Curie and her husband Pierre who are famous for discovering radium and for their work in radioactivity. It was chemically identified at the Metallurgical Labo-ratory (now Argonne National Laboratory) at the University of Chicago. It was actually the third transuranium element to be discovered even though it is the second in the series. Curium-242 (half-life 163 days) and one free neutron were made by bombarding alpha particles onto a plutonium-239 target in the 60-inch cyclotron at Berkeley. Louis Werner and Isadore Perlman created a visible sample of curium-242 hydroxide at the University of California in 1947 by bombarding americium-241 with neutrons. Curium was made in its elemental form in 1951 for the first time

Isotopes

19 radioisotopes of curium have been characterized, with the most stable being Cm-247 with a half-life of 1.56 x 107 years, Cm-248 with a half-life of 3.40 x 105 years, Cm-250 with a half-life of 9000 years, and Cm-245 with a half-life of 8500 years. All of the remaining radioactive isotopes have half-lifes that are less than 30 years, and the majority of these have half ifes that are less than 33 days. This element also has 4 meta states, with the most stable being Cm-244m (t1/2 34 ms). The isotopes of curium range in atomic weight from 233.051 amu (Cm-233) to 252.085 amu (Cm-252).



Previous Page

Berkelium

Berkelium is a synthetic element in the periodic table that has the symbol Bk, atomic number 97 and atomic weight of 247. It is a Actinoid.

• Name: Berkelium• Symbol: Bk• Atomic number: 97• Atomic weight: 247• Standard state: solid at 298 K• CAS Registry ID: 7440-40-6• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: unknown, but probably metallic and silvery white or grey in

appearance• Classification: Metallic

A radioactive metallic element in the actinide series, berkelium was first synthesized by bombarding americium with alpha particles (helium ions) and was named after Berkeley, California. Berkelium was the fifth transuranic element to be synthesized.


Weighable amounts of berkelium-249 (half-life 314 days) make it possible to deter-mine some of its properties using macroscopic quantities. As of 2004 it had not been isolated in its elemental form, but it is predicted to be a silvery metal that would easi-ly oxidize in air at elevated temperatures and would be soluble in dilute mineral acids.X-ray diffraction techniques have been used to identify various berkelium com-

pounds such as berkelium dioxide (BkO2), berkelium fluoride (BkF3), berkelium oxy-chloride (BkOCl), and berkelium trioxide (BkO3). In 1962 visible amounts of berkeli-um chloride were isolated that weighed 3 billionth of a gram. This was the first time visible amounts of a pure berkelium compound were produced. Like other actinides, berkelium bio-accumulates in skeletal tissue. This element has no known uses outside of basic research and plays no biological role.

History

Berkelium was first synthesized by Glenn T. Seaborg, Albert Ghiorso, Stanley G. Thompson, and Kenneth Street, Jr at the University of California, Berkeley in Decem-ber 1949. The team used a cyclotron to bombard a milligram-sized target of americi-um-241 with alpha particles to produce berkelium-243 (half-life 4.5 hours) and two free neutrons. One of the longest lived isotopes of the element, berkelium-249 (half-life 320 days), was later synthesized by subjecting a curium-244 target with an intense beam of neutrons.

Isotopes

19 radioisotopes of berkelium have been characterized, with the most stable being Bk-247 with a half-life of 1380 years, Bk-248 with a half-life of >9 years, and Bk-249 with a half-life of 320 days. All of the remaining radioactive isotopes have half-lifes that are less than 5 days, and the majority of these have half lifes that are less than 5 hours. This element also has 2 meta states, with the most stable being Bk-248m (t1/2 23.7 hours). The isotopes of berkelium range in atomic weight from 235.057 amu (Bk-235) to 254.091 amu (Bk-254).



Previous Page

Californium

Californium is a synthetic element in the periodic table that has the symbol Cf, atom-ic number 98 and atomic weight of 251 It is a Actinoid.

• Name: Californium• Symbol: Cf• Atomic number: 98• Atomic weight: 251• Standard state: solid at 298 K• CAS Registry ID: 7440-71-3• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: unknown, but probably metallic and silvery white or grey in


A radioactive transuranic element, californium has very few uses and was discovered by bombarding curium with alpha particles (helium ions).


Weighable amounts of californium make it posible to determine some of its proper-ties using macroscopic quantities. Californium-252 (half-life 2.6 years) is a very strong neutron emitter and is thus extremely radioactive and harmful (one microgram spon-taneously emits 170 million neutrons per minute). The decay of californium-254 (55-day half-life) may have been detected through telescopes in supernovae remnants. Californium-249 is formed from the beta decay of berkelium-249 and most other cal-ifornium isotopes are made by subjecting berkelium to intense neutron in a nuclear reactor. The element does have some specialist applications dealing with its radioac-tivity but otherwise is largely too difficult to produce to have useful significance as a material.

Two of its few uses:* In neutron moisture gauges which are in turn used to find water and oil layers in

oil wells.

* As a portable neutron source in gold and silver prospecting via on-the-spot activa-tion analysis. As of 2004, californium has not been isolated in its metallic form. The only californi-

um ion that is stable in aqueous solution is californium (III). Californium has no bio-logical role and only a few californium compounds have been made and studied. In-cluded among these are: californium oxide (CfO3), californium trichloride (CfCl3) and californium oxychloride (CfOCl).

History

Californium was first synthesized by University of California, Berkeley researchers Stanely Thompson, Kenneth Street, Jr., Albert Ghiorso and Glenn T. Seaborg in 1950. It was the sixth transuranium element to be discovered and the team announced their discovery on March 17, 1950. It was named after the U.S. state of California and for the University of California, Berkeley (which is nicknamed "Cal").To produce element 98, the team bombarded a microgram-sized target of curium-242

with 35 MeV alpha particles in the 60-inch Berkeley cyclotron to produced atoms of californium-245 (half-life 44 minutes) and a free neutron.

Isotopes

19 radioisotopes of californium have been characterized, with the most stable being Cf-251 with a half-life of 898 years, Cf-249 with a half-life of 351 years, andCf-250 with a half-life of 13 years. All of the remaining radioactive isotopes have half-lifes that are less than 2.7 years, and the majority of these have half lifes that are less than 20 min-utes. The isotopes of californium range in atomic weight from 237.062 amu (Cf-237) to 256.093 amu (Cf-256).



Previous Page

Einsteinium

Einsteinium is a synthetic element in the periodic table that has the symbol Es, atom-ic number 99 and atomic weight of 252. It is a Actinoid.

• Name: Einsteinium• Symbol: Es• Atomic number: 99• Atomic weight: 252• Standard state: solid at 298 K• CAS Registry ID: 7429-92-7• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: unknown, but probably metallic and silvery white or grey in


A metallic highly radioactive transuranic element (7th in the series) in the actinides, einsteinium is produced by bombarding plutonium with neutrons and was discovered in the debris of the first hydrogen bomb test. It was named after Albert Einstein and has no known uses. Tracer studies using the isotope Es-253 show that einsteinium has chemical properties typical of a heavy trivalent, actinide element.

History

Einsteinium was first identified in December 1952 by Albert Ghiorso at the University of California, Berkeley and another team headed by G.R. Choppin at Los Alamos Na-tional Laboratory. Both were examining debris from the first hydrogen bomb test of November, 1952 (see Operation Ivy). They discovered the isotope einsteinium-253 (half-life 20.5 days) that was made by the nuclear fusion of 15 neutrons with uranium-238 (which then went through seven beta decays). These findings were kept secret until 1955 due to Cold War tensions, however. In 1961, enough einsteinium was synthesized to prepare a macroscopic amount of Es-253. This sample weighed about 0.01 mg and was measured using a special balance. The material produced was used to produce mendelevium. Further einsteinium has been produced at the Oak Ridge National Lab-oratory's High Flux Isotope Reactor in Tennessee by bombarding plutonium-239 with

neutrons. Around 3 mg was created over a four year program of irradiation and then chemical separation from a starting 1 kg of plutonium isotope.

Isotopes

17 radioisotopes of einsteinium have been characterized, with the most stable being Es-252 with a half-life of 471.7 days, Es-254 with a half-life of 275.7 days, Es-255 with a half-life of 39.8 days, and Es-253 with a half-life of 20.47 days. All of the remaining ra-dioactive isotopes have half-lifes that are less than 40 hours, and the majority of these have half lifes that are less than 30 minutes. This element also has 3 meta states, with the most stable being Es-254m (t1/2 39.3 hours). The isotopes of einsteinium range in atomic weight from 240.069 amu (Es-240) to 257.096 amu (Es-257).



Previous Page

Fermium

Fermium is a synthetic element in the periodic table that has the symbol Fm, atomic number 100 and atomic weight of 257. It is a Actinoid.

• Name: Fermium• Symbol: Fm• Atomic number: 100• Atomic weight: 257• Standard state: presumably a solid at 298 K• CAS Registry ID: 7440-72-4• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: unknown, but probably metallic and silvery white or grey in


A highly radioactive metallic transuranic element of the actinide series, fermium is made by bombarding plutonium with neutrons and is named after nuclear physicist Enrico Fermi.


Only small amounts of fermium have ever been produced or isolated. Thus relatively little is known about its chemical properties. Only the (III) oxidation state of the ele-ment appears to exist in aqueous solution. Fermium-254 and heavier isotopes can be synthesized by intense neutron bombardment of lighter elements (especially urani-um and plutonium). During this, successive neutron captures mixed with beta decays build the fermium isotope. The intense neutron bombardment conditions needed to create fermium exist in thermonuclear explosions and can be replicated in the labora-tory (such as in the High Flux Isotope Reactor at Oak Ridge National Laboratory). The synthesis of element 102 (nobelium) was confirmed when fermium-250 was chemically identified. There are no known uses of fermium outside of basic research. Fermium is the eighth transuranic element.

History

Fermium (after Enrico Fermi) was first discovered by a team led by Albert Ghiorso in 1952. The team found fermium-255 in the debris of the first hydrogen-bomb explosion (see Operation Ivy). That isotope was created when uranium-238 combined with 17 neutrons in the intense temperature and pressure of the explosion (eight beta decays also occurred to create the element). The work was overseen by the University of Cal-ifornia Radiation Laboratory, Argonne National Laboratory, and Los Alamos Scientific Laboratory.All these findings were kept secret until 1955 due to Cold War tensions, however. In

late 1953 and early 1954 a team from the Nobel Institute of Physics in Stockholm bom-barded a uranium-238 target with oxygen-16 ions, producing an alpha-emitter with an atomic weight of ~250 and with 100 protons (in other words, element 100-250). The Noble team did not claim discovery but the isotope they produced was later positively identified as fermium-250.

Isotopes

17 radioisotopes of ermium have been characterized, with the most stable being Fm-257 with a half-life of 100.5 days, Fm-253 with a half-life of 3 days, Fm-252 with a half-life of 25.39 hours, and Fm-255 with a half-life of 20.07 hours. All of the remaining radioactive isotopes have half-lifes that are less than 5.4 hours, and the majority of these have half lifes that are less than 3 minutes. This element also has 1 meta state, Fm-250m (t1/2 1.8 seconds). The isotopes of fermium range in atomic weight from 242.073 amu (Fm-242) to 259.101 amu (Fm-259).



Previous Page

Mendelevium

Mendelevium (also known as unnilunium) is a synthetic element in the periodic table with the symbol Md, (formerly Mv) atomic number 101 and atomic weight of 258. It is a Actinoid.

• Name: Mendelevium• Symbol: Md• Atomic number: 101• Atomic weight: 258• Standard state: presumably a solid at 298 K• CAS Registry ID: 7440-11-1• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: unknown, but probably metallic and silvery white or grey in


A metallic radioactive transuranic element of the actinides, mendelevium is synthe-sized by bombarding einsteinium with alpha particles and was named after Dmitri Mendeleev.


Researchers have shown that mendelevium has a moderately stable dipositive (II) ox-idation state in addition to the more characteristic (for actinide elements) tripositive (III) oxidation state. Md-256 has been used to find out some of the chemical properties of this element while in an aqueous solution. There are no other uses of mendelevium and only trace amounts of the element have ever been produced.

History

Mendelevium (for Dmitri Mendeleev) was first synthesized by Albert Ghiorso (team leader), Glenn T. Seaborg, Bernard Harvey, and Greg Choppin in early 1955. The team produced Md-256 (half-life of 76 minutes) when they bombarded an einsteinium-253 target with alpha particles (helium nuclei) in the Berkeley Radiation Laboratory's 60-

inch cyclotron (Md-256 was synthesized one atom at a time). Element 101 was the ninth transuranic element synthesized.

Isotopes

15 radioisotopes of mendelevium have been characterized, with the most stable being Md-258 with a half-life of 51.5 days, Md-260 with a half-life of 31.8 days, and Md-257 with a half-life of 5.52 hours. All of the remaining radioactive isotopes have half-lifes that are less than 97 minutes, and the majority of these have half lifes that are less than 5 minutes. This element also has 1 meta state, 258m-Md (t1/2 57 minutes). The iso-topes of mendelevium range in atomic weight from 245.091 amu (Md-245) to 260.104 amu (Md-260).



Previous Page

Nobelium

Nobelium, also known as unnilbium is a synthetic element in the periodic table that has the symbol No, atomic number 102 and atomic weight of 259. It is a Actinoid.

• Name: Nobelium• Symbol: No• Atomic number: 102• Atomic weight: 259• Standard state: presumably a solid at 298 K• CAS Registry ID: 10028-14-5• Group in periodic table:• Group name: Actinoid• Period in periodic table: 7 (actinoid)• Block in periodic table: f-block• Colour: unknown, but probably metallic and silvery white or grey in


A radioactive metallic transuranic element in the actinide series, nobelium is synthe-sized by bombarding curium with carbon ions. It was first identified by a team led by Albert Ghiorso and Glenn T. Seaborg in 1958.


Little is known about nobelium and only small quantities of it have ever been pro-duced. Its has no uses whatsoever outside of the laboratory. Its most stable isotope, nobelium-259, has a half-life of 58 minutes and decays to fermium-255 through alpha decay or to mendelevium-259 through electron capture.

History

Nobelium (named for Alfred Nobel) was first synthesized by Albert Ghiorso, Glenn T. Seaborg, John R. Walton and TorbÃ¸rn Sikkeland in April 1958 at the University of California, Berkeley. The team used the new heavy-ion linear accelerator (HILAC) to bombard a curium target (95% Cm-244 and 4.5% Cm-246) with carbon-12 ions to make nobelium-254 (half-life 55 seconds). Their work was confirmed by Soviet researchers in Dubna.

A year earlier, however, physicists at the Nobel Institute in Sweden announced that they had synthesized an isotope of element 102. The team reported that they creat-ed an isotope with a half-life of 10 minutes at 8.5 MeV after bombarding curium-244 with carbon-13 nuclei. Based on this report, the Commission on Atomic Weights of the International Union of Pure and Applied Chemistry assigned and accepted the name nobelium and the symbol No for the "new" element. Subseqent Russian and American efforts to repeat the experiment failed.In 1966 researchers at UC Berkeley confirmed the 1958 experiments and went on to

show the existence of nobelium-254 (half-life 55 s), nobelium-252 (half-life 2.3 s), and nobelium-257 (half-life 23 s). The next year Ghiorso's group decided to retain the name nobelium for element 102.Nobelium was the most recent element "of which the news had come to Harvard"

when Tom Lehrer wrote "The Elements Song" and was therefore the element with the highest atomic number to be included.

Isotopes

13 radioisotopes of nobelium have been characterized, with the most stable being No-259 with a half-life of 58 minutes, No-255 with a half-life of 3.1 minutes, and No-253 with a half-life of 1.7 minutes. All of the remaining radioactive isotopes have half-lifes that are less than 56 seconds, and all of these have half lifes that are less than 2.4 sec-onds. This element also has 1 meta state, No-254m (t1/2 0.28 seconds).The known isotopes of nobelium range in atomic weight from 249.088 u (No-249) to

262.108 u (No-262). The primary decay mode before the most stable isotope, No-259, is alpha emission, and the primary mode after is spontaneous fission. The primary decay products before No-259 are element 100 (fermium) isotopes, and the primary products after are energy and subatomic particles.



Previous Page

Lawrencium

Lawrencium is a synthetic element in the periodic table that has the symbol Lr, atom-ic number 103 and atomic weight of 262. It is a Actinoid.

• Name: Lawrencium• Symbol: Lr• Atomic number: 103• Atomic weight: 262• Standard state: presumably a solid at 298 K• CAS Registry ID: 22537-19-5• Group in periodic table: 3• Group name: (none)• Period in periodic table: 7• Block in periodic table: d-block• Colour: unknown, but probably metallic and silvery white or grey in


A short-lived radioactive transuranic rare earth element, lawrencium is synthesized from californium and has no known uses.


The appearance of this element is unknown, however it is most likely silvery-white or gray and metallic. If sufficient amounts of lawrencium were produced, it would pose a radiation hazard. Very little is known about the chemical properties of this element but some preliminary work on a few atoms has indicated that it behaves similarly to the actinides.Lawrencium was, and often still is, grouped with the actinide chemical series in the

periodic table. However, unlike all other rare earths, element 103 is a d-block element and therefore is increasingly being placed with the other d-block elements in the transition metal chemical series.

History

Lawrencium was discovered by Albert Ghiorso, Torbjorn Sikkeland, Almon Larsh and Robert M. Latimer on February 14, 1961 at the Berkeley Radiation Laboratory (now

called Lawrence Berkeley National Laboratory) on the University of California, Berke-ley campus. It was produced by bombarding a 3 milligram target composed of three isotopes of californium with boron-10 and B-11 ions in the Heavy Ion Linear Accelera-tor ( HILAC ).The transmutation nuclei became electrically charged, recoiled with a helium atmo-

sphere and were collected on a thin copper conveyor tape. This tape was then moved in order to place the collected atoms in front of a series of solid-state detectors. The Berkeley team reported that the isotope 103-257 was detected in this manner and de-cayed by emitting an 8.6 MeV alpha particle with a half-life of 4.2 seconds.In 1967, researchers in Dubna, Russia reported that they were not able to confirm an

alpha emitter with a half-life of 4.2 seconds as 103-257. This assignment has since been changed to Lr-258 or Lr-259. Eleven isotopes of element 103 have been synthesized with Lr-262 being the longest lived with a half-life of 216 minutes ( it decays into no-belium-256 ). The isotopes of lawrencium decay via alpha emission, spontaneous fis-sion and electron capture (in order or most to least common types).The origin of the name, preferred by the American Chemical Society, is in reference

to Ernest O. Lawrence, inventor of the cyclotron. The symbol Lw was originally used but in 1963 it was changed to Lr. In August 1997 the International Union of Pure and Applied Chemistry ( IUPAC ) ratified the name lawrencium and symbol Lr during a meeting in Geneva.



Previous Page

Rutherfordium

Rutherfordium is a chemical element in the periodic table that has the symbol Rf, atomic number 104 and atomic weigh of 265. It is a Transactinide element.

• Name: Rutherfordium• Symbol: Rf• Atomic number: 104• Atomic weight: 265• Standard state: presumably a solid at 298 K• CAS Registry ID: 53850-36-5• Group in periodic table: 4• Group name: (none)• Period in periodic table: 7• Block in periodic table: d-block• Colour: unknown, but probably metallic and silvery white or grey in


This is a highly radioactive synthetic element whose most stable isotope has a half life of less than 70 seconds. This element therefore is not used for anything and little is known about it. Rutherfordium is the first transactinide element and it is predicted to have chemical properties similar to hafnium.

History

Rutherfordium (named in honor of Ernest Rutherford) was reportedly first synthe-sized in 1964 at the Joint Nuclear Research Institute at Dubna (U.S.S.R.). Researchers there bombarded plutonium with accelerated 113 to 115 MeV neon ions and claimed that they detected nuclear fission tracks in a special type of glass with a microscope which indicated the presence of a new element.In 1969 researchers at the University of California, Berkeley synthesized the element

by subjecting californium-249 and carbon-12 to high energy collisions. The UC group also stated that they could not reproduce the earlier synthesis by Soviet scientists.This resulted in an element naming controversy; Since the Soviets claimed that it was

first detected in Dubna, Dubnium (Db) was suggested, as was Kurchatovium and sym-bol Ku for element 104, in honor of Igor Vasilevich Kurchatov (1903-1960), former Head of Soviet Nuclear Research. The Americans, however, proposed.

Rutherfordium (symbol Rf) for the new element to honor Ernest Rutherford, a not-ed nuclear physicist from New Zealand. The International Union of Pure and Applied Chemistry (IUPAC) adopted Unnilquadium (symbol Unq) as a temporary name for this element. However in 1997 they resolved the dispute and adopted the current name.



Previous Page

Dubnium

Dubnium is a chemical element in the periodic table that has the symbol Db, atomic number 105 and atomic weight of 262. It is a Transactinide element.

• Name: Dubnium• Symbol: Db• Atomic number: 105• Atomic weight: 262• Standard state: presumably a solid at 298 K• CAS Registry ID: 53850-35-4• Group in periodic table: 5• Group name: (none)• Period in periodic table: 7• Block in periodic table: d-block• Colour: unknown, but probably metallic and silvery white or grey in


This is a highly radioactive synthetic element whose most stable isotope has a half life of 16 hours (dubnium-268). This relatively high stability compared to the surround-ing elements on the periodic table gives evidence that by manipulating the number of neutrons in a nucleus, one can alter the stabilities of such nuclei.

History

Dubnium (named after Dubna, Russia) was reportedly first synthesized in 1967 at the Joint Institute for Nuclear Research in Dubna, Russia (reportedly producing element 105-260 and element 105-261 by bombarding americium-243 with neon-22). In late April 1970 researchers led by Albert Ghiorso working at the University of California, Berke-ley had positively identified element 105.The American team synthesized the element by bombarding a target californium-249

with a beam of 84 MeV nitrogen nuclei in the Heavy Ion Linear Accelerator (a particle accelerator), which produced element 105-260 with a half-life of 1.6 seconds. Atoms of element 105 were detected conclusively on March 5, 1970 but there is evidence that this element had already been formed at Berkeley a year earlier using the same meth-od.The Berkeley scientists later tried to confirm the Soviet findings using more sophis-

ticated methods but were not successful. They proposed that the new element should be named hahnium (symbol Ha) in honor of the late German scientist Otto Hahn. Con-sequently this was the name that most American and Western European scientists used.An element naming controversy erupted over what to name this element after Rus-

sian researchers protested. The International Union of Pure and Applied Chemistry (IUPAC) thus adopted unnilpentium (symbol Unp) as a temporary name for this ele-ment. However in 1997 they resolved the dispute and adopted the current name, dub-nium (symbol Db), after the city that contains the Russian Joint Institute for Nuclear Research.



Previous Page

Seaborgium

Seaborgium is a chemical element in the periodic table that has the symbol Sg, atom-ic number 106 and atomic weight of 271. It is probably a Transactinide element.

• Name: Seaborgium• Symbol: Sg• Atomic number: 106• Atomic weight: 271• Standard state: presumably a solid at 298 K• CAS Registry ID: 54038-81-2• Group in periodic table: 6• Group name: (none)• Period in periodic table: 7• Block in periodic table: d-block• Colour: unknown, but probably metallic and silvery white or grey in


It was also known as "unnilhexium" (Unh), and at one time "rutherfordium" was sug-gested. Seaborgium is a synthetic element whose most stable isotope 266Sg has a half-life of 21 seconds. Its chemistry resembles that of tungsten.

History

Element 106 was discovered almost simultaneously by two different laboratories. In June 1974, a Soviet team led by G. N. Flerov at the Joint Institute for Nuclear Research at Dubna reported producing an isotope with mass number 259 and a half-life of 7 ms, and in September 1974, an American research team led by Albert Ghiorso at the Law-rence Radiation Laboratory at the University of California, Berkeley reported creating an isotope with mass number 263 and a half-life of 0.9 s.Because their work was independently confirmed first, the Americans suggested the

name seaborgium to honor the American chemist Glenn T. Seaborg. This name was extremely controversial because Seaborg was still alive. An international committee decided in 1992 that the Berkeley and Dubna laboratories should share credit for the discovery.An element naming controversy erupted and as a result IUPAC adopted unnilhexi-

um (symbol Unh) as a temporary name for this element. In 1994 a committee of IUPAC

recommended that element 106 be named rutherfordium and adopted a rule that no element can be named after a living person. This ruling was fiercely objected to by the American Chemical Society. Critics pointed out that a precedent had been set in the naming of einsteinium during Albert Einstein's life. In 1997, as part of a compromise involving elements 104 to 108, the name seaborgium for element 106 was recognized internationally.



Previous Page

Bohrium

Bohrium is a chemical element in the periodic table that has the symbol Bh and atom-ic number 107 and atomic weight of 264 It is a Transactinide element.

• Name: Bohrium• Symbol: Bh• Atomic number: 107• Atomic weight: 264• Standard state: presumably a solid at 298 K.• CAS Registry ID: 54037-14-8• Group in periodic table: 7• Group name: (none)• Period in periodic table: 7• Block in periodic table: d-block• Colour: unknown, but probably metallic and silvery white or grey in

appearance.• Classification: Metallic

It is a synthetic element whose most stable isotope, Bh-262, has a half-life of 102 ms.

History

It was synthesized in 1976 by a Soviet team led by Y. Oganessian at the Joint Institute for Nuclear Research at Dubna, who produced isotope 261Bh with a half-life of 1-2 ms (later data give a half life of around 10 ms). They did this by bombarding bismuth-204 with heavy nuclei of chromium-54. In 1981 a German research team led by P. Armbrust-er and G. Münzenberg at the Gesellschaft für Schwerionenforschung (Institute for Heavy Ion Research) at Darmstadt were also able to confirm the Soviet team's results and produce bohrium, this time the longer-lived Bh-262.The Germans suggested the name nielsbohrium to honor the Danish physicist Niels

Bohr. The Soviets had suggested this name be given to element 105 (dubnium). There was an element naming controversy as to what the elements from 101 to 109 were to be called; thus IUPAC adopted unnilseptium (symbol Uns) as a temporary name for this element. In 1994 a committee of IUPAC recommended that element 107 be named bohrium. While this conforms to the names of other elements honoring individuals, where only the surname is taken, it was opposed by many who were concerned that it could be confused with boron. Despite this, the name bohrium for element 107 was

recognized internationally in 1997



Previous Page

HassiumHassium is a chemical element in the periodic table that has the symbol Hs, atomic

number 108 Atomic weight 277. It is a Transactinide element.

• Name: Hassium• Symbol: Hs• Atomic number: 108• Atomic weight: 277• Standard state: presumably a solid at 298 K• CAS Registry ID: 54037-57-9• Group in periodic table: 8• Group name: (none)• Period in periodic table: 7• Block in periodic table: d-block• Colour: unknown, but probably metallic and silvery white or grey in


It is a synthetic element whose most stable isotope is Hs-265, with a half-life of 2 ms.

HistoryIt was first synthesized in 1984 by a German research team led by Peter Armbruster

and Gottfried MÃ¼nzenberg at the Institute for Heavy Ion Research at Darmstadt. The name hassium was proposed by them, derived from the Latin name for the German state of Hessen where the institute is located.There was an element naming controversy as to what the elements from 101 to 109

were to be called; thus IUPAC adopted unniloctium (symbol Uno) as a temporary name for this element. In 1994 a committee of IUPAC recommended that element 108 be named hahnium. The name hassium was adopted internationally, however, in 1997.


MeitneriumMeitnerium is a chemical element in the periodic table that has the symbol Mt, atom-

ic number 109 and atomic weight of 276. It is a Transactinide element.

• Name: Meitnerium• Symbol: Mt• Atomic number: 109• Atomic weight 276• Standard state: presumably a solid at 298 K• CAS Registry ID: 54038-01-6• Group in periodic table: 9• Group name: (none)• Period in periodic table: 7• Block in periodic table: d-block• Colour: unknown, but probably metallic and silvery white or grey in


It is a synthetic element whose most stable isotope is Mt-266 with a half-life of 3.4 ms.

HistoryMeitnerium was first synthesized on August 29, 1982 by a German research team led

by Peter Armbruster and Gottfried MÃ¼nzenberg at the Institute for Heavy Ion Re-search at Darmstadt.The team did this by bombing a target of bismuth-209 with ac-celerated nuclei of iron-58. The creation of this element demonstrated that nuclear fusion techniques could be used to make new, heavy nuclei.The name meitnerium was suggested in honor of the Austrian-Swedish physicist and

mathematician Lise Meitner, but there was an element naming controversy as to what the elements from 101 to 109 were to be called; thus IUPAC adopted unnilennium (sym-bol Une) as a temporary, systematic element name. However in 1997 they resolved the dispute and adopted the current name.



Previous Page

DarmstadtiumDarmstadtium (formerly ununnilium) is a chemical element in the periodic table that

has the symbol Ds, atomic number 110, and atomic weight of 281. Making it one of the super-heavy atoms and it probably is a Metallic element.

• Name: Darmstadtium• Symbol: Ds• Atomic number: 110• Atomic weight: 281• Standard state: presumably a solid at 298 K• CAS Registry ID: 54083-77-1• Group in periodic table: 10• Group name: (none)• Period in periodic table: 7• Block in periodic table: d-block• Colour: unknown, but probably metallic and silvery white or grey in


It is a synthetic element and decays in thousandths of a second. Due to its presence in Group 10 it is believed to likely be metallic and solid.

HistoryIt was first created on November 9, 1994 at the Gesellschaft für Schwerionenfor-

schung (GSI) in Darmstadt, Germany. It has never been seen and only a few atoms of it have been created by the nuclear fusion of isotopes of lead and nickel in a heavy ion accelerator (nickel atoms are the ones accelerated and bombarded into the lead).Scientists are not always serious, so some suggested the name policium for the new

element, because, 110 is the telephone number of the German police. The element was named after the place of its discovery, Darmstadt (actually, the GSI is located in Wixhausen, a small suburb north of Darmstadt). The new name was given to it by the IUPAC in August 2003.


RoentgeniumRoentgenium (former temporary name: unununium) is a chemical element in the

periodic table that has the symbol Rg, (formerly Uuu) atomic number 111 and atomic weight of 280. It is a synthetic element . Probably metallic and solid.

• Name: Roentgenium• Symbol: Rg• Atomic number: 111• Atomic weight: 280• Standard state: presumably a solid at 298 K• CAS Registry ID: 54386-24-2• Group in periodic table: 11• Group name: (none)• Period in periodic table: 7• Block in periodic table: d-block• Colour: unknown, but probably metallic and silvery white or grey in


It has an atomic weight of 272 making it one of the super-heavy atoms. It is a synthet-ic element whose only known isotope has a half-life of around 15 ms before it decays into meitnerium. Due to its presence in Group 11 it is a transition metal and so proba-bly metallic and solid.

HistoryIt was first created at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt,

Germany on December 8, 1994. Only three atoms of it have been created (all 272Rg), by the fusion of bismuth-209 and nickel-64 in a linear accelerator. (Nickel was bombarded onto the target.)The name roentgenium was accepted as a permanent name on November 1, 2004 in

honor of Wilhelm Roentgen; before this date, the element was known under the tem-porary IUPAC systematic element name unununium.



Previous Page

Copernicium( formerly Ununbium Uub 112 )

Copernicium (koh-per-NIS-ee-Ém) is a chemical element with symbol Cn and atomic number 112 and atomic weight of 285. It is a Transactinide element.

• Name: Copernicium• Symbol: Cn• Atomic number: 112• Atomic weight: 285• Standard state: presumably a liquid at 298 K• CAS Registry ID: 54084-26-3• Group in periodic table: 12• Group name: (none)• Period in periodic table: 7• Block in periodic table: d-block• Colour: unknown, but probably metallic and silvery white or grey in


It is an extremely radioactive synthetic element that can only be created in a labora-tory. The most stable known isotope, copernicium-285, has a half-life of approximately 29 seconds, but it is possible that this copernicium isotope may have an isomer with a longer half-life, 8.9 min.[citation needed] Copernicium was first created in 1996 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany. It is named after the astronomer Nicolaus Copernicus.

History

It was first created on February 9, 1996 at the Gesellschaft fur Schwerionenforschung (GSI) in Darmstadt, Germany. This element was created by fusing a zinc atom with a lead atom by accelerating zinc nuclei into a lead target in a heavy ion accelerator.Un-unbium is a temporary IUPAC systematic element name’In the periodic table of the elements, it is a d-block element, which belongs to trans-

actinide elements. During reactions with gold, it has been shown to be a volatile met-al and a group 12 element.Copernicium is calculated to have several properties that differ between it and its

lighter homologues, zinc, cadmium and mercury; the most notable of them is with-drawing two 6d-electrons before 7s ones due to relativistic effects, which confirm copernicium as an undisputed transition metal.Copernicium is also calculated to show a predominance of the oxidation state +4,

while mercury shows it in only one compound at extreme conditions and zinc and cadmium do not show it at all. It has also been predicted to be more difficult to oxi-dise copernicium from its neutral state than the other group 12 elements.In total, approximately 75 atoms of copernicium have been detected using various

nuclear reactions

Naming

Copernicium was named after Nicolaus Copernicus, a scientist who showed that the Earth moves around the Sun, and not the other way round.

Chemical

Copernicium is the last member of the 6d series of transition metals and the heaviest group 12 element in the periodic table, below zinc, cadmium and mercury. It is pre-dicted to differ significantly from the lighter group 12 elements. Due to stabilization of 7s electronic orbitals and destabilization of 6d ones caused by relativistic effects

IsotopesCopernicium has no stable or naturally-occurring isotopes. Several radioactive iso-

topes have been synthesized in the laboratory, either by fusing two atoms or by ob-serving the decay of heavier elements. Six different isotopes have been reported with atomic masses from 281 to 285, and 277, two of which, copernicium-283 and copernici-um-285, have known metastable states. Most of these decay predominantly through alpha decay, but some undergo spontaneous fission.The isotope copernicium-283 was instrumental in the confirmation of the elements flerovium and livermorium. Also Known As:

Ununbium Uub 112Ununbium is a chemical element in the periodic table that has symbol Uub and has

the atomic number 112. Element 112 is one of the superheavy elements and its atoms decompose through the emission of alpha particles with a half life of only about 240 Âµs



Previous Page

Ununtrium

Ununtrium is the temporary name of an unconfirmed synthetic element in the peri-odic table that has the temporary symbol Uut, atomic number 113 and atomic weight of 284. It is a Transactinide element.

• Name: Ununtrium• Symbol: Uut• Atomic number: 113• Atomic weight: 284• Standard state: presumably a solid at 298 K• CAS Registry ID: 54084-70-7• Group in periodic table: 13• Group name: (none)• Period in periodic table: 7• Block in periodic table: p-block• Colour: unknown, but probably metallic and silvery white or grey in


It is placed as the heaviest member of the group 13 (IIIA) elements although a suf-ficiently stable isotope is not known at this time that would allow chemical experi-ments to confirm its position as a heavier homologue to thallium. It was first detect-ed in 2003 in the decay of ununpentium and was synthesized directly in 2004. Only fourteen atoms of ununtrium have been observed to date. The longest-lived isotope known is 286Uut with a half-life of ~20 s, allowing first chemical experiments to study its chemistry.

HistoryOn February 1, 2004, ununtrium and ununpentium were reported by a team com-

posed of Russian scientists at Dubna (Joint Institute for Nuclear Research), and Amer-ican scientists at the Lawrence Livermore National Laboratory. Their discovery of the element still awaits confirmation.On September 28, 2004, a team of Japanese scientists declared that they succeeded in

synthesizing the element.


Flerovium

( formerly ununquadium Uuq 114)

Flerovium (formerly ununquadium) is a radioactive, superheavy artificial chemical element with symbol Fl and atomic number 114 and Atomic weight 289. It is a Transac-tinide element.

• Name: Flerovium• Symbol: Fl• Atomic number: 114• Atomic weight: 289• Standard state: presumably a solid at 298 K• CAS Registry ID: 54085-16-4• Group in periodic table: 14• Group name: (none)• Period in periodic table: 7• Block in periodic table: p-block• Colour: unknown, but probably metallic and silvery white or grey in appearance• Classification: Metallic

It is an extremely radioactive element that has only been created in the laboratory and has not been observed in nature.

History

From the late 1940s to the early 1960s, the early days of the synthesis of heavier and heavier transuranium elements, it was predicted that since such heavy elements did not occur in nature, they would have shorter and shorter half-lives to spontaneous fission, until they stopped being able to exist altogether at around element 108 (now known as hassium). Initial work in the synthesis of the actinides appeared to confirm this.About 80 decays of atoms of flerovium have been observed to date, 50 directly and 30

from the decay of the heavier elements livermorium and ununoctium. All decays have been assigned to the five neighbouring isotopes with mass numbers 285 - 289. The longest-lived isotope currently known is 289Fl with a half-life of ~2.6 s, although there is evidence for a nuclear isomer, 289bFl, with a half-life of ~66 s, that would be one of the longest-lived nuclei in the superheavy element region.


Previous Page

Chemical studies performed in 2007 indicate that flerovium may possess some non-eka-lead properties, in which case it might behave as the first superheavy element that exhibits some noble-gas-like properties due to relativistic effects.

Discovery

Flerovium was first synthesized in December 1998 by a team of scientists at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia led by Yuri Oganessian, who bombarded a target of plutonium-244 with accelerated nuclei of calcium-48:A single atom of flerovium, decaying by alpha emission with a half-life of 30 seconds,

was detected. This observation was assigned to the isotope flerovium-289 and was subsequently published in January 1999. However, while the experiment was later re-peated, an isotope with these decay properties was never found again and hence the exact identity of this activity is unknown. It is possible that it is due to a metastable isomer, namely 289mFl.The element is named after Russian physicist Georgy Flyorov, the founder of the Joint

Institute for Nuclear Research in Dubna, Russia, where the element was discovered. The name was adopted by IUPAC on May 31, 2012.

Also Known As:Ununquadium Uuq 114

Ununquadium is the temporary name of a radioactive chemical element in the peri-odic table that has the temporary symbol Uuq has the atomic number 114 and atomic weight of 289 Ununquadium does not occur naturally.

From Wikipedia, the free encyclopedia.

Ununpentium

Ununpentium is the temporary name of an unconfirmed synthetic superheavy ele-ment in the periodic table that has the temporary symbol Uup, atomic number 115 and atomic weight of 288. It is in the Pnictogen group.

• Name: Ununpentium• Symbol: Uup• Atomic number: 115• Atomic weight: 288• Standard state: presumably a solid at 298 K• CAS Registry ID: 54085-64-2• Group in periodic table: 15• Group name: Pnictogen• Period in periodic table: 7• Block in periodic table: p-block• Colour: unknown, but probably metallic and silvery white or grey in


History

On February 1, 2004, the synthesis of ununpentium and ununtrium were reported in Physical Review C by a team composed of Russian scientists at Dubna University's Joint Institute for Nuclear Research and American scientists at the Lawrence Liver-more National Laboratory . Their discovery of the element still awaits confirmationThe team reported that they bombarded americium (element 95) with calcium (el-

ement 20) to produce four atoms of ununpentium (element 115). These atoms, they report, decayed to ununtrium (element 113) in a fraction of a second. The ununtrium produced then existed for 1.2 seconds before decaying into known elements.

Ununpentium is a temporary IUPAC systematic element name. Ununpentium was theorized to be inside the island of stability. This probably explains why it was men-tioned regularly in popular culture before it was actually created: * In the world of UFO conspiracy theory culture during the 1980s and 1990s, Bob

Lazar asserted that ununpentium functioned as "fuel" for UFOs, being "stepped up" to ununhexium under "particulate bombardment," and that the ununhexium's decay products would include antimatter. These processes are considered implausible in


Previous Page

terms of nuclear physics, not least due to the very short half-lives of both elements. * As a reference to this kind of UFO conspiracy theory, in the X-COM game series

there is an element called elerium-115 or just elerium ("elerium-115" probably being an error as in this form the number would have referred to the number of nucleons in-stead of the atomic number, meaning that elerium would have no neutrons, which is not possible). * A fictional stable isotope of ununpentium occurs in the game Dark Reign. * A fictional stable isotope of ununpentium occurs in the movie The Core.


Livermorium

( formerly Ununhexium Uuh 116)Livermorium is a chemical element in the periodic table that has the symbol Lv, atom-

ic number 116 and atomic weight of 293. It is in the Chalcogen group.

• Name: Livermorium• Symbol: Uuh• Atomic number: 116• Atomic weight: 293• Standard state: presumably a solid at 298 K• CAS Registry ID: 54100-71-9• Group in periodic table: 16• Group name: Chalcogen• Period in periodic table: 7• Block in periodic table: p-block• Colour: unknown, but probably metallic and silvery white or grey in


Naming

Livermorium is historically known as eka-polonium. Ununhexium (Uuh) was the tem-porary IUPAC systematic element name. Scientists usually refer to the element simply as element 116 (or E116). According to IUPAC recommendations, the discoverer(s) of a new element has the right to suggest a name.The discovery of livermorium was recognized by JWG of IUPAC on 1 June 2011, along

with that of flerovium. According to the vice-director of JINR, the Dubna team want-ed to name element 116 moscovium, after the Moscow Oblast in which Dubna is locat-ed. However, the name Livermorium and the symbol Lv were adopted on May 31, 2012 after an approval process by the IUPAC. The name recognises the Lawrence Livermore National Laboratory, within the city of Livermore, California, USA, which collaborated with JINR on the discovery. The city in turn is named after the American rancher Rob-ert Livermore, a naturalized Mexican citizen of English birth.

Discovery

On July 19, 2000, scientists at Dubna (JINR) detected a single decay from an atom of


Previous Page

livermorium following the irradiation of a Cm-248 target with Ca-48 ions. The re-sults were published in December 2000. This 10.54 MeV alpha-emitting activity was originally assigned to 292Lv due to the correlation of the daughter to previously as-signed 288Fl. That assignment was later altered to 289Fl, and hence this activity was correspondingly changed to 293Lv. Two further atoms were reported by the institute during their second experiment between April - May 2001.

History

In 1999, researchers at Lawrence Berkeley National Laboratory announced the discov-ery of elements 116 and 118 (see ununoctium), in a paper published in Physical Review Letters. The following year, they published a retraction after other researchers were unable to duplicate the results. In June 2002, the director of the lab announced that the original claim of the discovery of these two elements had been based on data fab-ricated by the principal author Victor Ninov.In January, 2001 the Joint Institute for Nuclear Research, Dubna, published results

that described the decay of the isotope 292Uuh, which was produced in the reaction of 248Cm with 48Ca. It has a half-life of about 0.6 milliseconds (0.0006 seconds) and decayed into 288Uuq. On May 11th, 2001, the institute reported synthesizing a second atom, and that the properties confirmed a region of "enhanced" stability. Confirma-tion of these results is still pending.Ununhexium in popular culture:In the world of UFO conspiracy theory culture during the 1980s and 1990s, Bob Lazar

asserted that ununpentium functioned as "fuel" for UFOs, being "stepped up" to un-unhexium under "particulate bombardment," and that the ununhexium's decay prod-ucts would include antimatter. These processes are considered implausible in terms of nuclear physics, not least due to the very short half-lives of both elements. Also Known As:Ununhexium Uuh 116

Ununhexium was the temporary name of an unconfirmed synthetic superheavy el-ement in the periodic table that has the temporary symbol Uuh and has the atomic number 116.


Ununseptium

Ununseptium is the temporary name of an undiscovered chemical element in the pe-riodic table that has the temporary symbol Uus, atomic number 117 and atomic weight of 294. It is in the Halogen. group.

• Name: Ununseptium• Symbol: Uus• Atomic number: 117• Atomic weight: 294• Standard state: presumably a solid at 298 K• CAS Registry ID: 87658-56-8• Group in periodic table: 17• Group name: Halogen• Period in periodic table: 7• Block in periodic table: p-block• Colour: unknown, but probably metallic and dark in appearance• Classification: Unknown

In the periodic table ununseptium is located in the group 17, all previous members of which are halogens. The element is unlikely to be a halogen, however, and will prob-ably show differences, although a few key properties such as melting and boiling points and first ionization are expected to follow the periodic trends. While lighter isotopes are agreed in the literature to be very unstable, there are signs that the su-per-heavy isotopes may be much more stable.

History

Ununseptium has not yet been discovered. Ununseptium is a temporary IUPAC sys-tematic element name.It is the second-heaviest element of all created. Its discovery was first announced in

2010, when the element was claimed to have been created in Dubna by a joint Russian - American collaboration. Another experiment in 2011 created one of its daughters us-ing a different method, partially proving the results of the discovery experiment, and the original experiment was repeated successfully in 2012. The International Union of Pure and Applied Chemistry (IUPAC), however, has made no comment on whether or not the element can be recognized as discovered.


Previous Page

Discovery

The experiment began in June 2009 and, in January 2010, scientists at the Flerov Lab-oratory of Nuclear Reactions announced internally that they had succeeded in detect-ing the decay of a new element with Z = 117 via two decay chains of an odd-odd isotope (undergoing 6 alpha decays before undergoing a spontaneous fission) and of an odd-even one (3 alpha decays before fission).On April 9, 2010 an official report was released in the journal Physical Review Letters. It revealed that the isotopes mentioned in the previous chains referred to 294Uus and 293Uus,

Naming

Using Mendeleev's nomenclature for unnamed and undiscovered elements, ununsep-tium should be known as eka-astatine or dvi-iodine. In 1979 IUPAC published recom-mendations according to which the element was to be called ununseptium (with the corresponding symbol of Uus), a systematic element name as a placeholder, until the discovery of the element is confirmed and a name is decided on. The recommenda-tions are largely ignored among scientists, who call it "element 117", with the symbol of (117) or even simply 117. No official name has yet been suggested for the element. According to current guidelines from IUPAC, the ultimate name for all new elements should end in "-ium", which means the name for ununseptium will end in "-ium", not "-ine", even if ununseptium turns out to be a halogen, which traditionally have names ending in "-ine".

Atomic and Physical

Ununseptium is a member of group 17 in the periodic table, below the five halogens. ununseptium will behave similar to the halogens in many respects. However, notable differences are likely to arise; a largely contributing effect is the spinn-orbit (SO) in-teraction, or, more exactly, subshell splitting. For many theoretical purposes,


Ununoctium

Ununoctium is the temporary name of an undiscovered chemical element in the peri-odic table that has the temporary symbol Uuo, atomic number 118 and atomic weight of 294. It is in the Noble gas group.

• Name: Ununoctium• Symbol: Uuo• Atomic number: 118• Atomic weight: 294• Standard state: presumably a gas at 298 K• CAS Registry ID: 54144-19-3• Group in periodic table: 18• Group name: Noble gas• Period in periodic table: 7• Block in periodic table: p-block• Colour: unknown, but probably a colourless gas• Classification: Non-metallic

If discovered, it would probably share the properties of its group, the noble gases, resembling radon in its chemical properties. It would only be the second radioactive, gaseous element, which is an interesting fact, and the first standard semiconductive gas, which is also interesting.

History

In 1999, researchers at Lawrence Berkeley National Laboratory announced the dis-covery of elements 116 and 118, in a paper published in Physical Review Letters. The following year, they published a retraction after other researchers were unable to duplicate the results. In June 2002, the director of the lab announced that the original claim of the discovery of these two elements had been based on data fabricated by principal author Victor Ninov Ununoctium is a temporary IUPAC systematic element name.

Unsuccessful Synthesis Attempts

In late 1998, Polish physicist Robert Smolanczuk published calculations on the fusion of atomic nuclei towards the synthesis of superheavy atoms, including ununoctium.


Previous Page

His calculations suggested that it might be possible to make ununoctium by fusing lead with krypton under carefully controlled conditions.In 1999, researchers at Lawrence Berkeley National Laboratory made use of these pre-

dictions and announced the discovery of ununhexium (now livermorium) and ununoc-tium, in a paper published in Physical Review Letters, and very soon after the results were reported in Science.


Group 1: Alkali Metals or Llthium family

• Lithium Li• Sodium Na• Potassium K• Rubidium Rb• Caesium Cs (also spelled cesium)• Francium Fr

The Alkali Metals are a group of chemical elements in the periodic table with very similar properties: they are all shiny, soft, silvery, highly reactive metals at standard temperature and pressure and readily lose their outermost electron to form cations with charge +1.:28 They can all be cut easily with a knife due to their softness, expos-ing a shiny surface that tarnishes rapidly in air due to oxidation. Because of their high reactivity, they must be stored under oil in sealed glass ampoules to prevent reaction with air. In the modern IUPAC nomenclature, the alkali metals comprise the group 1 elements, excluding hydrogen (H), which is nominally a group 1 element but not nor-mally considered to be an alkali metal as it rarely exhibits behaviour comparable to that of the alkali metals. All the alkali metals react with water, with the heavier alkali metals reacting more vigorously than the lighter ones.

The Alkali Metals are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). This group lies in the s-block of the periodic table as all alka-li metals have their outermost electron in an s-orbital. The alkali metals provide the best example of group trends in properties in the periodic table, with elements exhib-iting well-characterized homologous behaviour.

All the discovered Alkali Metals occur in nature. Experiments have been conducted to attempt the synthesis of ununennium (Uue), which is likely to be the next member of the group, but they have all met with failure. However, ununennium may not be an alkali metal due to relativistic effects, which are predicted to have a large influence on the chemical properties of superheavy elements.

From Wikipedia, the free encyclopedia


Previous Page

Alkaline Earth Metals or Beryllium family

• Beryllium Be• Magnesium Mg• Calcium Ca• Strontium Sr• Barium Ba• Radium Ra

The Alkaline Earth Metals are a group of chemical elements in the periodic table with very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure and readily lose their two outermost electrons to form cations with charge +2. In the modern IUPAC nomenclature, the alkaline earth metals comprise the group 2 elements.

The Alkaline Earth Metals are beryllium (Be), magnesium (Mg), calcium (Ca), stron-tium (Sr), barium (Ba), and radium (Ra). This group lies in the s-block of the periodic table as all alkaline earth metals have their outermost electron in an s-orbital.

All the discovered Alkaline Earth Metals occur in nature. Experiments have been conducted to attempt the synthesis of unbinilium (Ubn), which is likely to be the next member of the group, but they have all met with failure. However, unbinilium may not be an alkaline earth metal due to relativistic effects, which are predicted to have a large influence on the chemical properties of superheavy elements


Group 3:Scandium family (consisting of the Rare Earth Metal plus the Actinides)

• Scandium Sc• Yttrium Y• Lanthanoids• Lanthanum La• Cerium Ce• Praseodymium Pr• Neodymium Nd• Promethium Pm• Samarium Sm• Europium Eu• Gadolinium Gd• Terbium Tb• Dysprosium Dy• Holmium Ho• Erbium Er• Thulium Tm• Ytterbium Yb• Lutetium Lu• Actinides• Actinium Ac• Thorium Th• Protactinium Pa• Uranium U• Neptunium Np• Plutonium Pu• Americium Am• Curium Cm• Berkelium Bk• Californium Cf• Einsteinium Es• Fermium Fm


Previous Page

• Mendelevium Md• Nobelium No• Lawrencium Lr• Lutetium Lu

The group 3 elements are a group of chemical elements in the periodic table. This group, like other d-block groups, should contain four elements, but it is not agreed what elements belong in the group. Scandium (Sc) and yttrium (Y) are always includ-ed, but the other two spaces are usually occupied by lanthanum (La) and actinium (Ac), or by lutetium (Lu) and lawrencium (Lr); less frequently, it is considered the group should be expanded to 32 elements (with all the Lanthanoids and Actinoids included) or contracted to contain only scandium and yttrium. The group itself has not acquired a trivial name; however, scandium, yttrium and the lanthanides are sometimes called rare earth metals.

Three group 3 elements occur naturally, scandium, yttrium, and either lanthanum or lutetium. Lanthanum continues the trend started by two lighter members in general chemical behavior, while lutetium behaves more similarly to yttrium. This is in accor-dance with the trend for period 6 transition metals to behave more similarly to their upper periodic table neighbors.

This trend is seen from hafnium, which is almost identical chemically to zirconium, to mercury, which is quite distant chemically from cadmium, but still shares with it al-most equal atomic size and other similar properties. They all are silvery-white metals under standard conditions. The fourth element, either actinium or lawrencium, has only radioactive isotopes. Actinium, which occurs only in trace amounts, continues the trend in chemical behavior for metals that form tripositive ions with a noble gas configuration; synthetic lawrencium is calculated and partially shown to be more sim-ilar to lutetium and yttrium.

So far, no experiments have been conducted to synthesize any element that could be the next group 3 element. Unbiunium (Ubu), which could be considered a group 3 element if preceded by lanthanum and actinium, might be synthesized in the near future, it being only three spaces away from the current heaviest element known, un-unoctium.


Group 4: Titanium family

• Titanium Ti• Zirconium Zr• Hafnium Hf• Rutherfordium Rf

The Group 4 elements are a group of chemical elements in the periodic table. In the modern IUPAC nomenclature, Group 4 of the periodic table contains titanium (Ti), zirconium (Zr), hafnium (Hf) and rutherfordium (Rf). This group lies in the d-block of the periodic table. The group itself has not acquired a trivial name; it belongs to the broader grouping of the transition metals.

The three Group 4 elements that occur naturally are titanium (Ti), zirconium (Zr) and hafnium (Hf). The first three members of the group share similar properties; all three are hard refractory metals under standard conditions. However, the fourth element rutherfordium (Rf), has been synthesized in the laboratory; none of its isotopes have been found occurring in nature. All isotopes of rutherfordium are radioactive. So far, no experiments in a supercollider have been conducted to synthesize the next mem-ber of the group, either unpentquadium (Upq) or unpenthexium (Uph), and it is un-likely that they will be synthesized in the near future.



Previous Page

Group 5: Vanadium family

• Vanadium V• Zirconium Zr• Tantalum Ta• Dubnium Db

A Group 5 element is a chemical element in the fifth group in the periodic table. In the modern IUPAC nomenclature, Group 5 of the periodic table contains vanadium (V), niobium (Nb), tantalum (Ta) and dubnium (Db). This group lies in the d-block of the pe-riodic table. The group itself has not acquired a trivial name; it belongs to the broader grouping of the transition metals.

The lighter three Group 5 elements occur naturally and do share similar properties; all three are hard refractory metals under standard conditions. The fourth element, dubnium, has been synthesized in the laboratory, but it has not been found occurring in nature, with half-life of the most stable isotope, dubnium-268, being only 28 hours, and other isotopes even more radioactive. To date, no experiments in a supercollider have been conducted to synthesize the next member of the group, either unpentpen-tium (Upp) or unpentseptium (Ups). As unpentpentium and unpentseptium are both late period 8 elements it is unlikely that these elements will be synthesized in the near future.


Group 6: Chromium family

• Chromium Cr• Molybdenum Mo• Tungsten W• Seaborgium Sg

A Group 6 element is one in the series of elements in group 6 (IUPAC style) in the pe-riodic table, which consists of the transition metals chromium (Cr), molybdenum (Mo), tungsten (W), and seaborgium (Sg). The period 8 elements of group 6 are likely to be either unpenthexium (Uph) or unpentoctium (Upo) (if possible, since drip instabilities may imply that the periodic table ends at unbihexium). Neither of them have been synthesized, and it is unlikely that this will happen in the near future.

Like other groups, the members of this family show patterns in its electron configu-ration, especially the outermost shells resulting in trends in chemical behavior:



Previous Page

Group 7: Manganese family

• Manganese Mn• Technetium Tc• Rhenium Re• Bohrium Bh

A Group 7 element is one in the series of elements in group 7 (IUPAC style) in the pe-riodic table, which consists of manganese (Mn), technetium (Tc), rhenium (Re), and bohrium (Bh). All known elements of group 7 are transition metals.

Like other groups, the members of this family show patterns in their electron config-urations, especially the outermost shells resulting in trends in chemical behavior.Bohrium has not been isolated in pure form, and its properties have not been conclu-

sively observed; only manganese, technetium, and rhenium have had their properties experimentally confirmed. All three elements are typical silvery-white transition met-als, hard, and have high melting and boiling points

Group 7 contains the two naturally occurring transition metals discovered last: tech-netium and rhenium. Manganese has been known for millennia. Rhenium was discov-ered when Masataka Ogawa found what he thought was element 43 in thorianite, but this was dismissed; recent studies by H. K. Yoshihara suggest that he discovered rhe-nium instead.


Group 8: Iron family

• Iron Fe• Ruthenium Rh• Osmium Os• Hassium Hf

A Group 8 element is one in the series of elements in group 8 (IUPAC style) in the pe-riodic table, which consists of the transition metals iron (Fe), ruthenium (Ru), osmium (Os) and hassium (Hs).

Like other groups, the members of this family show patterns in its electron configu-ration, especially the outermost shells resulting in trends in chemical behavior.

Group 8 is the new IUPAC name for this group; the old style name was "group VIIIA" in the old European system or "group VIIIB" in the old US system. Group 8 must not be confused with the group with the old-style group names of either VIIIB (European system) or VIIIA (US system); that group is now called group 18.



Previous Page

Group 9: Cobalt family

• Cobalt Co• Rhodium Rh• Iridium Ir• Meitnerium Mt

In modern IUPAC nomenclature, Group 9 of the periodic table contains the elements cobalt (Co), rhodium (Rh), iridium (Ir), and meitnerium (Mt). These are all d-block tran-sition metals. All known isotopes of meitnerium are radioactive with short half-lives, and it is not known to occur in nature; only minute quantities have been synthesized in laboratories.

Like other groups, the members of this family show patterns in its electron con-figuration, especially the outermost shells resulting in trends in chemical behavior, though rhodium curiously does not follow the pattern.


Group 10: Nickel family

• Nickel Ni• Palladium Pd• Platinum Pt• Darmstadtium Ds

A Group 10 element is one in the series of elements in group 10 (IUPAC style) in the pe-riodic table, which consists of the d-block transition metals nickel (Ni), palladium (Pd), platinum (Pt), and darmstadtium (Ds). All known isotopes of Ds are radioactive with short half-lives, and it is not known to occur in nature; only minute quantities have been synthesized in laboratories.

Like other groups, the members of this family show patterns in its electron configu-ration, especially the outermost shells (though for this family it is particularly weak with palladium being an exceptional case). The relativistic stabilization of the 7s orbit-al is the explanation to the unusual electron configuration of darmstadtium.



Previous Page

Group 11: Coinage Metals or Copper family

• Copper Cu• Silver Ag• Gold Au• Roentgenium Rg

A Group 11 element is one in the series of elements in group 11 (IUPAC style) in the pe-riodic table, consisting of transition metals copper (Cu), silver (Ag), and gold (Au).Roentgenium (Rg) belongs to this group of elements based on its theoretical elec-

tronic configuration, but it is a short-lived transactinide with a 22.8 seconds half-life that has only been observed in laboratory conditions.

Although at various times societies have used other metals in coinage including al-uminium, lead, nickel, stainless steel, tin, and zinc, the name "coinage metals" is used to highlight the special physio-chemical properties that make this series of metals uniquely well suited for monetary purposes. These properties include ease of identifi-cation, resistance to tarnish, extreme difficulty in counterfeiting, durability, fungibil-ity and a reliable store of value unmatched by any other metals known.

History

All the elements of the group except roentgenium have been known since prehistoric times, as all of them occur in metallic form in nature and no extraction metallurgy has to be used to produce them.


Group 12: Zinc family

• Zinc Zn• Cadmium Cd• Mercury Hg• Copernicium Cn

A group 12 element is one of the elements in group 12 (IUPAC style) in the periodic table. This includes zinc (Zn), cadmium (Cd) and mercury (Hg). The further inclusion of copernicium (Cn) in group 12 is supported by recent experiments on individual coper-nicium atoms.

The elements in group 12 are usually considered to be d-block elements, but not tran-sition elements as the d-shell is full.

The three group 12 elements that occur naturally are zinc, cadmium and mercury. They are all widely used in electric and electronic applications, as well as in various alloys. The first two members of the group share similar properties as they are solid metals under standard conditions. Mercury is the only metal that is a liquid at room temperature. While zinc is very important in the biochemistry of living organisms, cadmium and mercury are both highly toxic. As copernicium does not occur in nature, it has to be synthesized in the laboratory.



Previous Page

Group 13: Triels, Boron group or Boron family

• Boron B• Aluminium Al• Gallium Ga• Indium In• Thallium Ti• Ununtrium Uut

The boron group is the series of elements in group 13 (IUPAC style) of the periodic table, comprising boron (B), aluminium (Al), gallium (Ga), indium (In), thallium (Tl), and ununtrium (Uut).

The elements in the boron group are characterized by having three electrons in their outer energy levels (valence layers). These elements have also been referred to as earth metals and as triels.Boron is classified as a metalloid while the rest, with the possible exception of un-

untrium, are considered poor metals. Ununtrium has not yet been confirmed to be a poor metal and, due to relativistic effects, might not turn out to be one. Boron occurs sparsely, probably because bombardment by the subatomic particles produced from natural radioactivity disrupts its nuclei. Aluminium occurs widely on earth, and in-deed is the third most abundant element in the Earth's crust (8.3%). Gallium is found in the earth with an abundance of 13 ppm. Indium is the 61st most abundant element in the earth's crust, and thallium is found in moderate amounts throughout the plan-et. Ununtrium is never found in nature and therefore is termed a synthetic element.Several group 13 elements have biological roles in the ecosystem. Boron is a trace

element in humans and is essential for some plants. Lack of boron can lead to stunted plant growth, while an excess can also cause harm by inhibiting growth. Aluminium has neither a biological role nor significant toxicity and is considered safe. Indium and gallium can stimulate metabolism; gallium is credited with the ability to bind it-self to iron proteins. Thallium is highly toxic, interfering with the function of numer-ous vital enzymes, and has seen use as a pesticide

HistoryThe boron group has had many names over the years. According to former conven-

tions it was Group IIIB in the European naming system and Group IIIA in the Ameri-can. The group has also gained two collective names, "earth metals" and "triels". The latter name is derived from the Latin prefix tri- ("three") and refers to the three va-lence electrons that all of these elements, without exception, have in their valence shells.

Boron was known to the ancient Egyptians, but only in the mineral borax. The metal-loid element was not known in its pure form until 1808, when Humphry Davy was able to extract it by the method of electrolysis. Davy devised an experiment in which he dissolved a boron-containing compound in water and sent an electric current through it, causing the elements of the compound to separate into their pure states

Characteristics

Like other groups, the members of this family show patterns in their electron config-uration, especially the outermost shells, resulting in trends in chemical behavior:



Previous Page

Group 14: Tetrels, Carbon group or Carbon family

• Carbon C• Silicon Si• Germanium Ge• Tin Sn• Lead Pb• Flerovium Fl - formerly ununquadium

The carbon group is a periodic table group consisting of carbon (C), silicon (Si), ger-manium (Ge), tin (Sn), lead (Pb), and flerovium (Fl) formerly ununquadium.In modern IUPAC notation, it is called Group 14. In the old IUPAC and CAS systems, it

was called Group IVB and Group IVA, respectively. In the field of semiconductor phys-ics, it is still universally called Group IV. The group was once also known as the tetrels (from Greek tetra, four), stemming from the Roman numeral IV in the group names, or (not coincidentally) from the fact that these elements have four valence electrons.

History

Carbon, tin, and lead, are a few of the elements well known in the ancient world to-gether with sulfur, iron, copper, mercury, silver, and gold.Carbon as an element was discovered by the first human to handle charcoal from a

fire. Modern carbon chemistry dates from the development of coals, petroleum, and natural gas as fuels and from the elucidation of synthetic organic chemistry, both substantially developed since the 19th century.

Amorphous elemental silicon was first obtained pure in 1824 by the Swedish chemist Jons Jacob Berzelius; impure silicon had already been obtained in 1811. Crystalline ele-mental silicon was not prepared until 1854, when it was obtained as a product of elec-trolysis. In the form of rock crystal, however, silicon was familiar to the predynastic Egyptians, who used it for beads and small vases; to the early Chinese; and probably to many others of the ancients. The manufacture of glass containing silica was carried out both by the Egyptians at least as early as 1500 BCE - and by the Phoenicians.

Germanium is one of three elements the existence of which was predicted in 1871 by the Russian chemist Dmitri Mendeleev when he first devised his periodic table. Not until 1886, however, was germanium identified as one of the elements in a newly found mineral.

The origins of tin seem to be lost in history. It appears that bronzes, which are alloys

of copper and tin, were used by prehistoric man some time before the pure metal was isolated. Bronzes were common in early Mesopotamia, the Indus Valley, Egypt, Crete, Israel, and Peru. Much of the tin used by the early Mediterranean peoples apparently came from the Scilly Isles and Cornwall in the British Isles, where mining of the metal dates from about 300 - 200 BCE.

Lead is mentioned often in early Biblical accounts. The Babylonians used the metal as plates on which to record inscriptions. The Romans used it for tablets, water pipes, coins, and even cooking utensils; indeed, as a result of the last use, lead poisoning was recognized in the time of Augustus Caesar. Modern developments date to the ex-ploitation in the late 18th century of deposits in the Missouri - Kansas - Oklahoma area in the United States.



Previous Page

Group 15: Pnictogens or Nitrogen family

• Nitrogen N• Phosphorus P• Arsenic As• Antimony Sb• Bismuth Bi• Ununpentium Uup

The nitrogen group (also known as the pnictogens) is a periodic table group consist-ing of nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi) and unun-pentium (Uup) (unconfirmed).

In modern IUPAC notation, it is called Group 15. In the old IUPAC and CAS systems, it was called Group VB and Group VA, respectively (pronounced "group five B" and "group five A", "V" for the Roman numeral. In the field of semiconductor physics, it is still universally called Group V. The "five" ("V") in the historical names comes from the "pentavalency" of nitrogen, reflected by the stoichiometry of compounds such as N2O5.

History

The term "pnictogen" was suggested by the Dutch chemist Anton Eduard van Arkel in the early 1950s. It is also spelled "pnicogen" or "pnigogen". It comes from the Greek root pnikta ("suffocated things"), and thus the word "pnictogen" is also a reference to the German name for nitrogen (Stickstoff, "suffocating substance"). Hence, "pnicto-gen" could be translated as "suffocator maker". The word "pnictide" also comes from the same root.


Group 16: Chalcogens or Oxygen family

• Oxygen O• Sulfur S• Selenium Se• Tellurium Te• Polonium Po• Livermorium Lv

The chalcogens are the chemical elements in group 16 of the periodic table. This group is also known as the oxygen family. It consists of the elements oxygen (O), sul-fur (S), selenium (Se), tellurium (Te), the radioactive element polonium (Po), and the synthetic element livermorium (Lv).

The first four chalcogens (oxygen (O), sulfur (S), selenium (Se), tellurium (Te)) are all primordial on Earth. Polonium forms naturally after the decay of other elements, even though it is not primordial.Although all group 16 elements of the periodic table, including oxygen, are defined

as chalcogens, oxygen and oxides are usually distinguished from chalcogens and chal-cogenides. The term chalcogenide is more commonly reserved for sulfides, selenides, and tellurides, rather than for oxides.

Binary compounds of the chalcogens are called chalcogenides (rather than chalcides; however, this breaks the pattern of halogen/halide and pnictogen/pnictide).Although the word "chalcogen" is literally taken from Greek words being "cop-

per-former", the meaning is more in line with "copper-ore former" or more general-ly, "ore-former". These electronegative elements are strongly associated with met-al-bearing minerals, where they have formed water-insoluble compounds with the metals in the ores.

Properties

Members of this group show similar patterns in their electron configuration, espe-cially the outermost shells, resulting in similar trends in chemical behavior:Oxygen, sulfur, and selenium are non-metals, and tellurium and polonium are met-

alloid semiconductors (that means, their electrical properties are between those of a metal and an insulator). Nevertheless, tellurium, as well as selenium, is often referred to as a metal when in elemental form. Metal chalcogens are common as minerals.



Previous Page

Group 17: Halogens or Fluorine family

• Fluorine F• Chlorine Cl• Bromine Br• Iodine I• Astatine At• Ununseptium Uus

The halogens or halogen elements are a series of nonmetal elements from group 17 of the periodic table (formerly: VII, VIIA), comprising fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The artificially created element 117 (ununseptium) may also be a halogen.

The group of halogens is the only periodic table group which contains elements in all three familiar states of matter at standard temperature and pressure. Chlorine is a gas, bromine is a liquid and iodine is a solid. Fluorine could not be included due to its high reactivity.

History

In 1842 the Swedish chemist Baron Jöns Jakob Berzelius proposed the term "halogen" "salt" or "sea", (gÃ gnomai), "come to be" - for the four elements (fluorine, chlorine, bromine, and iodine) that produce a sea-salt-like substance when they form a com-pound with a metal. Earlier, in 1811, the word "halogen" had been proposed as a name for the newly discovered element chlorine, but Davy's proposed term for this element eventually won out.


Group 18: Noble gases or Helium family or Neon family

• Helium He• Neon Ne• Argon Ar• Krypton Kr• Xenon Xe• Radon Rn• Ununoctium Uuo

The noble gases are a group of chemical elements with very similar properties: un-der standard conditions, they are all odorless, colorless, monatomic gases, with very low chemical reactivity. The six noble gases that occur naturally are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn).For the first six periods of the periodic table, the noble gases are exactly the members

of group 18 of the periodic table. However, it is possible that due to relativistic effects, the group 14 element flerovium exhibits some noble-gas-like properties, instead of the group 18 element ununoctium.

The properties of the noble gases can be well explained by modern theories of atom-ic structure: their outer shell of valence electrons is considered to be "full", giving them little tendency to participate in chemical reactions, and it has been possible to prepare only a few hundred noble gas compounds. The melting and boiling points for each noble gas are close together, differing by less than 10°C (18°F); that is, they are liquids over only a small temperature range.

Neon, argon, krypton, and xenon are obtained from air using the methods of lique-faction of gases and fractional distillation. Helium is typically separated from natural gas, and radon is usually isolated from the radioactive decay of dissolved radium com-pounds. Noble gases have several important applications in industries such as light-ing, welding, and space exploration.

A helium-oxygen breathing gas is often used by deep-sea divers at depths of seawa-ter over 55 m (180 ft) to keep the diver from experiencing oxygen toxemia, the lethal effect of high-pressure oxygen, and nitrogen narcosis, the distracting narcotic effect of the nitrogen in air beyond this partial-pressure threshold. After the risks caused by the flammability of hydrogen became apparent, it was replaced with helium in blimps and balloons.

History


Previous Page

Noble gas is translated from the German noun Edelgas, first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity. The name makes an anal-ogy to the term "noble metals", which also have low reactivity. The noble gases have also been referred to as inert gases, but this label is now deprecated as many noble gas compounds are now known.

Rare gases is another term that was used, but this is also inaccurate because argon forms a fairly considerable part (0.94% by volume, 1.3% by mass) of the Earth's atmo-sphere.

The group 14 element Flerovium exhibits some noble-gas-like properties, instead of the group 18 element ununoctium


Alkaline Metal Elements

• Lithium Li 3• Sodium Na 11• Potassium K 19• Rubidium Rb 37• Caesium Cs 55• Francium Fr 87

Earth Metal Elements

• Beryllium Be 4• Magnesium Mg 12• Calcium Ca 20• Strontium Sr 38• Barium Ba 56• Radium Ra 88• Zinc Zn 30• Cadmium Cd 48• Mercury Hg 80• Aluminium Al 13• Gallium Ga 31• Indium In 49• Thallium Tl 81• Tin Sn 50• Lead Pb 82• Bismuth Bi 83



Previous Page

Non - Metal Elements

• Hydrogen H 1• Carbon C 6• Nitrogen N 7• Phosphorus P 15• Oxygen O 8• Sulfur S 16• Selenium Se 34• Fluorine F 9• Chlorine Cl 17• Bromine Br 35• Iodine I 53


Nobel Gas Elements

• Helium He 2• Neon Ne 10• Argon Ar 18• Krypton Kr 36• Xenon Xe 54• Radon Rn 86• Ununoctium Uuo 118


Actinoid Elements

• Actinium Ac 89• Thorium Th 90• Protactinium Pa 91• Uranium U 92• Neptunium Np 93• Plutonium Pu 94• Americium Am 95• Curium Cm 96• Berkelium Bk 97• Californium Cf 98• Einsteinium Es 99• Fermium Fm 100• Mendelevium Md 101• Nobelium No 102• Lawrencium Lr 103


Lanthanoid Elements

• Lanthanum La 57• Cerium Ce 58• Praseodymium Pr 59• Neodymium Nd 60


Previous Page

Semi - Metallic Elements

• Boron B 5• Silicon Si 14• Germanium Gm 32• Arsenic As 33• Antimony Sb 51• Tellurium Te 52• Polonium Po 84• Astatine At 85• Ununseptium Uus 117

From Wikipedia, the free encyclopedi

• Promethium Pm 61• Samarium Sm 62• Europium Eu 63• Gadolinium Gd 64• Terbium Tb 65• Dysprosium Dy 66• Holmium Ho 67• Erbium Er 68• Thulium Tm 69• Ytterbium Yb 70• Lutetium Lu 71


Transition Metal Elements

• Scandium Sc 21• Yttrium Y 39• Titanium Ti 22• Zirconium Zr 40• Hafnium Hf 72• Vanadium V 23• Niobium Nb 41• Tantalum Ta 73• Chromium Cr 24• Molybdenum Mo 42• Tungsten W 74• Manganese Mn 25• Technetium Tc 43• Rhenium Re 75• Iron Fe 26• Ruthenium Ru 44• Osmium Os 76• Cobalt Co 27• Rhodium Rh 45• Iridium Ir 77• Nickel Ni 28• Palladium Pd 46• Platinum Pt 78• Copper Cu 29• Silver Ag 47• Gold Au 79



Previous Page

Transactinides Elements

• Rutherfordium Rf 104• Dubnium Db 105• Seaborgium Sg 106• Bohrium Bh 107• Hassium Hs 108• Meitnerium Mt 109• Darmstadtium Ds 110• Roentgenium Rg 111• Copernicium Cn 112• Ununtrium Uut 113*• Flerovium Fl 114• Ununpentium Uup 115*• Livermorium Lv 116• Ununseptium Uus 117*• Ununoctium Uuo 118*

* The synthesis of these elements has not been officially attested by IUPAC, while in several cases previous syntheses have been confirmed by other institutions or other methods. The names and symbols given are provisional as no names for the elements have been agreed on.

Transactinide elements

In chemistry, transactinide elements (also, transactinides, or super-heavy elements) are the chemical elements with atomic numbers greater than those of the actinides, the heaviest of which is lawrencium (103).Transactinide elements are also transuranic elements, that is, have an atomic num-

ber greater than that of uranium (92), an actinide. The further distinction of having an atomic number greater than the actinides is significant in several ways:

The transactinide elements all have electrons in the 6d subshell in their ground state (and thus are placed in the d-block). The last actinide, lawrencium, also has one electron in the 6d subshell. Except for dubnium, even the longest-lasting isotopes of transactinide elements have extremely short half-lives, measured in seconds, or small-er units.

The element naming controversy involved the first five or six transactinide elements. These elements thus used three-letter systematic names for many years after their discovery had been confirmed. (Usually the three-letter names are replaced with two-letter names relatively shortly after a discovery has been confirmed.)Transactinides are radioactive and have only been obtained synthetically in laborato-

ries. None of these elements has ever been collected in a macroscopic sample. Trans-actinide elements are all named after nuclear physicists and chemists or important locations involved in the synthesis of the elements.

Chemistry Nobelist Glenn T. Seaborg who first proposed the actinide concept which led to the acceptance of the actinide series also proposed the existence of a transac-tinide series ranging from element 104 to 121 and a superactinide series approximately spanning elements 122 to 153. The transactinide seaborgium is named in his honor.The term transactinide is an adjective, and is not commonly used alone as a noun to

refer to the transactinide elements.

List of the transactinide elements IUPAC defines an element to exist if its lifetime is longer than 10-14 seconds, which is the time it takes for the nucleus to form an elec-tronic cloud.



Previous Page

Period 1 ElementsA period 1 element is one of the chemical elements in the first row (or period) of the

periodic table of the chemical elements. The periodic table is laid out in rows to illus-trate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical col-umns. The first period contains fewer elements than any other row in the table, with only two: hydrogen and helium. This situation can be explained by modern theories of atomic structure. In a quantum mechanical description of atomic structure, this peri-od corresponds to the filling of the 1s orbital. Period 1 elements obey the duet rule in that they need two electrons to complete their valence shell. The maximum number of electrons that these elements can accommodate is two, both in the 1s orbital. There-fore, period 1 can have only two elements.

Periodic trends

Hydrogen’s electron configuration is 1.Helium’s electron configuration is 2.

All other periods in the period table contain at least 8 elements, and it is often help-ful to consider periodic trends across the period. However, period 1 contains only two elements, so this concept does not apply here.

In terms of vertical trends down groups, helium can be seen as a typical noble gas at the head of Group 18, but as discussed below, hydrogren’s chemistry is unique and it is not easily assigned to any group.Position of period 1 elements in the periodic table

Although both hydrogen and helium are in the s-block, neither of them behaves sim-ilarly to other s-block elements. Their behaviour is so different from the other s-block elements that there is considerable disagreement over where these two elements should be placed in the periodic table.

• Hydrogen• Helium


Period 2 Elements

A period 2 element is one of the chemical elements in the second row (or period) of the periodic table. The periodic table is laid out in rows to illustrate recurring (period-ic) trends in the chemical behavior of the elements as their atomic number increases; a new row is started when chemical behavior begins to repeat, creating columns of elements with similar properties.

The second period contains the elements lithium, beryllium, boron, carbon, nitro-gen, oxygen, fluorine, and neon. This situation can be explained by modern theories of atomic structure. In a quantum mechanical description of atomic structure, this period corresponds to the filling of the 2s and 2p orbitals. Period 2 elements obey the octet rule in that they need eight electrons to complete their valence shell. The max-imum number of electrons that these elements can accommodate is ten, two in the 1s orbital, two in the 2s orbital and six in the 2p orbital. All of the elements in the period can form diatomic molecules except beryllium and neon.

Period 2 is the first period in the periodic table that periodic trends can be drawn from. Period 1, which only contains two elements (hydrogen and helium) is too small to draw any conclusive trends from it, especially because the two elements behave nothing like other s-block elements. Period 2 has much more conclusive trends. For all elements in period 2, as the atomic number increases, the atomic radius of the ele-ments decreases, the electronegativity increases, and the ionization energy increases

• Lithium• Beryllium• Boron• Carbon• Nitrogen• Oxygen• Fluorine• Neon



Previous Page

Period 3 Elements

A period 3 element is one of the chemical elements in the third row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illus-trate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when the periodic table skips a row and a chemical behaviour begins to repeat, meaning that elements with similar behavior fall into the same vertical columns. The third period contains eight elements: sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine, and argon. The first two, sodium and magnesium, are members of the s-block of the periodic table, while the others are members of the p-block. Note that there is a 3d orbital, but it is not filled until Period 4, such giving the period table its characteristic shape of "two rows at a time". All of the period 3 elements occur in nature and have at least one stable isotope.

• Sodium• Magnesium• Aluminium• Silicon• Phosphorus• Sulfur• Chlorine• Argon


Period 4 ElementsA period 4 element is one of the chemical elements in the fourth row (or period) of

the periodic table of the elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atom-ic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The fourth period contains 18 elements, beginning with potassium and ending with kryp-ton. As a rule, period 4 elements fill their 4s shells first, then their 3d and 4p shells, in that order, however there are exceptions, such as chromium.

PropertiesEvery single one of these elements are stable, and many are extremely common in

the earth’s crust and/or core. Many of the transition metals in period 4 are incredibly strong, and therefore commonly used in industry, especially iron. Copper is one of three elements that are not silver or gray in color, along with caesium and gold. Three adjacent elements are known to be toxic, with arsenic one of the most well-known poisons, selenium being toxic to humans in large quantities, and bromine, a very toxic liquid. Many elements are essential to humans’ survival, such as calcium being what forms bones

• Potassium• Calcium• Scandium• Titanium• Vanadium• Chromium• Manganese• Iron• Cobalt• Nickel• Copper• Zinc• Gallium• Germanium• Arsenic• Selenium• Bromine• Krypton



Previous Page

Period 5 ElementsA period 5 element is one of the chemical elements in the fifth row (or period) of the

periodic table of the elements. The periodic table is laid out in rows to illustrate re-curring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The fifth period contains 18 elements, beginning with rubidium and ending with xenon. As a rule, period 5 elements fill their 5s shells first, then their 4d, and 5p shells, in that order, however there are exceptions, such as rhodium.

Physical PropertiesThis period contains technetium, one of the two elements until lead that has no sta-

ble isotopes (along with promethium), as well as molybdenum and iodine, two of the heaviest elements with a known biological role, and Niobium has the largest magnet-ic known penetration depth of all the elements. Zirconium is one of the main com-ponents of zircon crystals, currently the oldest known minerals in the earth’s crust. Many later transition metals, such as rhodium, are very commonly used in jewelry due to the fact that they are incredibly shiny.This period is known to have a large number of exceptions to the Madelung rule.

• 37 Rb Rubidium Alkali metal • 38 Sr Strontium Alkaline earth metal • 39 Y Yttrium Transition metal • 40 Zr Zirconium Transition metal • 41 Nb Niobium Transition metal (*)• 42 Mo Molybdenum Transition metal *)• 43 Tc Technetium Transition metal • 44 Ru Ruthenium Transition metal (*)• 45 Rh Rhodium Transition metal (*)• 46 Pd Palladium Transition metal (*)• 47 Ag Silver Transition metal (*)• 48 Cd Cadmium Transition metal • 49 In Indium Other metal • 50 Sn Tin Other metal • 51 Sb Antimony Metalloid • 52 Te Tellurium Metalloid • 53 I Iodine Diatomic nonmetal • 54 Xe Xenon Noble gas(*) Exception to the Madelung rule


Period 6 Elements

A period 6 element is one of the chemical elements in the sixth row (or period) of the periodic table of the elements, including the lanthanides. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical be-haviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The sixth period contains 32 elements, tied for the most with period 7, beginning with caesium and ending with radon. Lead is currently the last stable element; all subsequent elements are radioactive, however bismuth has a half-life of more than 10 years, more than 1,000 times longer than the current age of the universe. As a rule, period 6 elements fill their 6s shells first, then their 4f, 5d, and 6p shells, in that order, however there are exceptions, such as cerium.

• 55 Cs Caesium Alkali metal • 56 Ba Barium Alkaline earth metal • 57 La Lanthanum Lanthanide [a] • 58 Ce Cerium Lanthanide • 59 Pr Praseodymium Lanthanide • 60 Nd Neodymium Lanthanide • 61 Pm Promethium Lanthanide • 62 Sm Samarium Lanthanide • 63 Eu Europium Lanthanide • 64 Gd Gadolinium Lanthanide • 65 Tb Terbium Lanthanide • 66 Dy Dysprosium Lanthanide • 67 Ho Holmium Lanthanide • 68 Er Erbium Lanthanide • 69 Tm Thulium Lanthanide • 70 Yb Ytterbium Lanthanide • 71 Lu Lutetium Lanthanide [a] • 72 Hf Hafnium Transition metal • 73 Ta Tantalum Transition metal • 74 W Tungsten Transition metal • 75 Re Rhenium Transition metal • 76 Os Osmium Transition metal • 77 Ir Iridium Transition metal • 78 Pt Platinum Transition metal• 79 Au Gold Transition metal• 80 Hg Mercury Transition metal • 81 Tl Thallium Post-transition metal


Previous Page

• 82 Pb Lead Post-transition metal • 83 Bi Bismuth Post-transition metal • 84 Po Polonium Post-transition metal • 85 At Astatine Halogen • 86 Rn Radon Noble gas

a Note that lutetium (or, alternatively, lanthanum) is considered to be a transition metal, but marked as a lanthanide, as it is considered so by IUPAC.


Period 7 Elements

A period 7 element is one of the chemical elements in the seventh row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The seventh period contains 32 elements, tied for the most with period 6, beginning with francium and ending with ununoctium, the heaviest element current-ly discovered. As a rule, period 7 elements fill their 7s shells first, then their 5f, 6d, and 7p shells, in that order, however there are exceptions, such as protactinium.

Properties

All elements of period 7 are radioactive. This period contains the actinides, which contains the heaviest naturally occurring element, californium; subsequent elements must be synthesized artificially. Whilst one of these (einsteinium) is now available in macroscopic quantities, most are extremely rare, having only been prepared in micro-gram amounts or less. The later, transactinide elements have only been identified in laboratories in batches of a few atoms at a time: of these, ununtrium, ununpentium and those beyond livermorium have not been recognised by the IUPAC.

Although the rarity of many of these elements means that experimental results are not very extensive, their periodic and group trends are less well defined than other periods. Whilst francium and radium do show typical properties of their respective groups, actinides display a much greater variety of behaviour and oxidation states than the lanthanides. These peculiarities are due to a variety of factors, including a large degree of spin-orbit coupling and relativistic effects, ultimately caused by the very high positive electrical charge from their massive atomic nuclei.

• 87 Fr Francium Alkali metal • 88 Ra Radium Alkaline earth metal • 89 Ac Actinium Actinide (*)• 90 Th Thorium Actinide (*)• 91 Pa Protactinium Actinide (*)• 92 U Uranium Actinide (*)• 93 Np Neptunium Actinide (*)• 94 Pu Plutonium Actinide • 95 Am Americium Actinide • 96 Cm Curium Actinide (*)• 97 Bk Berkelium Actinide


Previous Page

• 98 Cf Californium Actinide • 99 Es Einsteinium Actinide • 100 Fm Fermium Actinide • 101 Md Mendelevium Actinide • 102 No Nobelium Actinide • 103 Lr Lawrencium Actinide (probably) (**)• 104 Rf Rutherfordium Transition metal (probably)• 105 Db Dubnium Transition metal (?)• 106 Sg Seaborgium Transition metal (?)• 107 Bh Bohrium Transition metal (?)• 108 Hs Hassium Transition metal • 109 Mt Meitnerium Transition metal (?) • 110 Ds Darmstadtium Transition metal (?) • 111 Rg Roentgenium Transition metal (?) • 112 Cn Copernicium Transition metal (?)• 113 Uut Ununtrium Post-transition metal (?) • 114 Fl Flerovium Post-transition metal (?)• 115 Uup Ununpentium Post-transition metal (?) • 116 Lv Livermorium Post-transition metal (?) • 117 Uus Ununseptium Metalloid (?) • 118 Uuo Ununoctium Noble gas (?)

(?) Prediction

(*) Exception to the Madelung rule.

(**) Probably an exception to the Madelung rule.


Actinium Ac 89Aluminium Al 13Americium Am 95Antimony Sb 51Argon Ar 18Arsenic As 33Astatine At 85Barium Ba 56Berkelium Bk 97Beryllium Be 4Bismuth Bi 83Bohrium Bh 107Boron B 5 Bromine Br 35Cadmium Cd 48Caesium Cs 55 Calcium Ca 20Californium Cf 98Carbon C 6Cerium Ce 58Chlorine Cl 17Chromium Cr 24Cobalt Co 27Copernicium Cn 112Copper Cu 29Curium Cm 96Darmstadtium Ds 110Dubnium Db 105Dysprosium Dy 66Einsteinium Es 99Erbium Er 68Europium Eu 63Fermium Fm 100Flerovium Fl 114Fluorine F 9Francium Fr 87Gadolinium Gd 64Gallium Ga 31Germanium Gm 32Gold Au 79Hafnium Hf 72Hassium Hs 108Helium He 2Holmium Ho 67


Previous Page

Hydrogen H 1Indium In 49Iodine I 53Iridium Ir 77Iron Fe 26Krypton Kr 36Lanthanum La 57Lawrencium Lr 103 Lead Pb 82Lithium Li 3Livermorium Lv 116Lutetium Lu 71Magnesium Mg 12Manganese Mn 25Meitnerium Mt 109Mendelevium Md 101Mercury Hg 80Molybdenum Mo 42Neodymium Nd 60Neon Ne 10Neptunium Np 93Nickel Ni 28Niobium Nb 41Nitrogen N 7Nobelium No 102Osmium Os 76Oxygen O 8Palladium Pd 46Phosphorus P 15Platinum Pt 78Plutonium Pu 94Polonium Po 84Potassium K 19Praseodymium Pr 59Promethium Pm 61Protactinium Pa 91Radium Ra 88Rhenium Re 75Rubidium Rb 37Rutherfordium Rf 104Roentgenium Rg 111Rhodium Rh 45Radon Rn 86Ruthenium Ru 44Samarium Sm 62Scandium Sc 21Seaborgium Sg 106Selenium Se 34Silicon Si 14Silver Ag 47

Sodium Na 11Strontium Sr 38Sulfur S 16Tantalum Ta 73Technetium Tc 43Tellurium Te 52Terbium Tb 65Thallium Tl 81Thorium Th 90Thulium Tm 69Tin Sn 50Titanium Ti 22Tungsten W 74Ununoctium Uuo 118Ununpentium Uup 115Ununseptium Uus 117Ununtrium Uut 113Uranium U 92Vanadium V 23Xenon Xe 54Yttrium Y 39Ytterbium Yb 70Zinc Zn 30Zirconium Zr 40

Ununhexium Livermorium Lv 116Ununquadium Flerovium Fl 114Ununbium Copernicium Cn 112

Documents

The Periodic Table C