Metals Metals have been extracted and used for many thousands of yearsUses of Different Metals through history Copper Age (3200-2300 BC)Predominant Metal/Metal SubstituteCopper

Important PropertiesDoes not corrodeEasily extracted

Extraction/ProductionThe copper ore is heated with charcoal in a fire. Smelting in a reducing atmosphere.

UseOrnaments, domestic utensils, jewellery, weapons, mirrors

Important Alloy(s) in use at the timeNone

Working copper was difficult as the melting point needed was too great for wood fires to achieve. The finished products of copper were fairly soft. Copper tools didnt replace stone ones in use. Bronze Age (2300-700 BC)Predominant Metal/Metal SubstituteCopper, tin, bronze

Important Properties Tin heavy, hard and inertBronze harder metal than copper and tin, could be melted, moulded and worked more easily.

Extraction/ProductionTin ore heated with charcoal in a fire. Bronze formed when copper and tin ores heated with charcoal in a fire.

UseTin rarely used on its own. Bronze used to make tools and weapons.

Important Alloy(s) in use at the timeBronze

Around 2000 BC, bronze became prominent and used for tools and weapons throughout European and Asian continents. This led to technological difference between societies with bronze and those without it. Bronze was discovered when impure copper ores containing arsenic and lead minerals were smelted. The copper that formed had different physical properties due to presence of other metals. Arsenic bronze was a useful alloy as it was harder than pure copper and could make stronger and harder tools. Arsenic bronze was replaced by tin bronze, as tin bronze wasnt as brittle. Tin bronze was used to make cutting tools and was superior to copper as they maintained a sharper edge that could be readily resharpened. Iron Age (700 BC-AD 1)Predominant Metal/Metal Substitute Iron

Important Properties Hard, durable, tough

Extraction/ProductionAir blown into a fire to produce high temperatures for heating iron with charcoal.

UseTools and weapons

Important Alloy(s) in use at the timeCast iron (iron with carbon)

In order to extract iron from iron oxide, using wood-fires, you must generate a temperature higher than that of copper extraction. It wasnt until 1200 BC that humans developed a method and ability to forge iron into tools and weapons. The charcoal burned in the blast of air to form CO, reducing the iron ore to iron. Controlling the amount of carbon in iron was a problem. Blacksmiths developed a method of hammering the iron at red heat to squeeze out solid impurities and burn off the carbon. This iron is wrought iron. The technology improved by 1 AD that iron strips could be created. These were shaped into swords and strengthen chariot wheels. Pure iron was never obtained. Instead, various types of iron alloys like carbon-steels were formed. These readily corroded. Iron had been known to exist at least a thousand years before from samples of meteoric iron. Technology for extracting, processing and moulding spread out throughout Europe and Asia. Since it is much harder and stronger than bronze, most weapons and tools were made of iron instead. Modern Age (AD 1 to present) Predominant Metal/Metal Substitute Iron, aluminium

Important Properties Iron hard, durable toughAluminium lightweight, corrosion resistant, good tensile strength

Extraction/ProductionIron blast furnace Aluminium electrolysis

UseIron car bodies, roofing sheets, household appliances, machineryAluminium planes, car parts, drink containers, building, domestic use, high voltage transmission lines Copper electrical wiring, pipes and plumbing fittings, electroplating Zinc galvanising iron, protective paints, diecast alloys and brass, casing for dry cellsLead car batteries, plumbing and in solder, glaze for pottery

Important Alloy(s) in use at the timeCarbon steel, stainless steel, alloy steel with tungsten, magnesium, titanium

Technologies for producing iron and steel rapidly improved and quantities being used increased. Alloy steels were developing from about the late 1880s (order of tungsten steel, manganese steel, silicon steel, chromium steel, nickel steel, vanadium steel). Aluminium, tungsten, magnesium came into common use in the last 100 years. Future AgePredominant Metal/Metal Substitute Ceramics, plastics, composite material

Important Properties Ceramics high melting temperature, low density, high strength, stiffness, hardness, wear resistance and corrosion resistance, good electrical and thermal insulator Plastics hard or soft, doesnt corrode, flexible, tough, lightweight, easy to process at low temperaturesComposites overall properties superior to individual components

Extraction/ProductionCeramics extracted from clay or sand and fired in a kilnPlastics made mainly form fractions of crude oil through different processes Composite made as a combination of polymer and ceramic or metal and ceramic

UseCeramic includes glass windows, liquid crystal displays, optical fibres, cooking utensils, food storage, insulators Plastics electrical wire insulation, flexible tubing, bottles, carpet fibres, ropes, packing foams, lighting panels, hoses, pipes, toys, raincoats, electrical appliance components, valvesComposites sporting equipment, racing cars, structural and building materials

Alloys An alloy is a mixture of a metal with one or more other elements (usually metals). Most alloys ware examples of solid solutions. Examples include steel, bronze, solder.Alloys were discovered by accident due to the contamination of minerals by other mineral impurities. Arsenic bronze was discovered because copper minerals containing small quantities of arsenic minerals were smelted, resulting in an arsenic bronze. The properties of a metal are altered by the inclusion of atoms of another element .The inclusion of small amounts of other elements tend to disturb the regular arrangement of the crystal lattice, leading to a new lattice that is harder and less malleable. Properties of alloys can be varied by mixing metals in different proportions. Alloys tend to be poorer electrical conductors than their pure metal components. The presence of impurities disrupts the crystal lattice and creates defects. The colour of an alloy depends on the proportion of each component metal. For example, the 20c coin is silvery-grey due to the high nickel content, whereas the $1 coin is golden because of the high copper content. Alloy CompositionPropertiesUse

Brass 50-60% copper with zincLustrous gold appearancesHard but easily machinedPlumbing fittings, musical instruments, decorations

Solder 30-60% tin with leadLow melting pointAdheres firmly to other metals when moltenJoining metals together, particularly in electronics and plumbing

Mild steel< 0.2% carbon, mainly ironSofter, more malleable and ductile than higher carbon steels.Useful in car bodies, roofing and nails

Structural steel 0.3-0.6% carbon, mainly ironHigh tensile strengthHardSteel girders, rail tracks, axles

High carbon steels 0.6-1.3% carbon, mainly ironVery HardLow malleability and ductility Small tools such as axes

Stainless steelIron with 10-20% chromium, 5-20% nickelHardCorrosion resistant Food processing machinery, kitchen sink and appliances, cutlery, surgical and dental instruments, razor blades

Extraction of metalsOnly few metals, such as gold and silver, occur free in nature. Most metals occur as compounds in rock.Minerals are pure crystalline compounds occurring in Earths curst. Ores are compounds or mixture of compounds from which it is economic or commercially profitable to extract a desired substance such as a metal. Gangue is the unwanted waste of an ore after the mineral has been extracted. All metal compounds in rocks can be called minerals but only those that are commercially exploited are called ores. For an ore to be mined, it must contain a mineral in sufficiently high concentration to make the mining and extraction an economic proposition. Recently, the disposal of waste gangue has become controversial. Land and water pollution can result from the inappropriate disposal of this waste. In the process called rehabilitation, mining companies are careful to return mined areas to their original state (or as close as possible) when they have finished mining an area. Steps in the extraction of metals A chemical reaction is used to extract the metal from its ore. Every chemical reaction involves either the release or absorption of heat. The two main steps in the extraction of a metal are:1. Separation of the ore into the required minerals and unwanted gangue is a physical process and is carried out by techniques like froth flotation.2. Extraction of the metal from the mineral. This is a chemical process and is carried out by techniques such as roasting and electrolysis. In the case of gold, only separation is needed, and so in history people could simply the gold from gangue to obtain the metal, giving rise to famous gold rush and gold fever, since people hoped they could get rich quickly by hurrying to where gold had been discovered and finding the precious metal. The ease of extraction of metals Metals differ in their ease of extraction and this has led to their uses at different times throughout history. The metals found free, such as gold, or easiest to extract, such as copper, were the first used. Aluminium was difficult to extract so it was only relatively recently discovered extracted and used, even through it is the most abundant metal in the Earths crust. Since the extraction of metals from their ores involves the decomposition of compounds such as metal oxides, energy is needed to break the intermolecular bonds to produce a metal in its elemental form. Different compounds require different amounts of energy to bring about the decomposition by breaking bonds. The most active metals form the most stable compounds so need the most energy to decompose them. 3 types:- The easiest metal compounds to decompose (e.g. CuS) can be decomposed by roasting with carbon. - The next easiest (e.g. Fe2O3) can be decomposed by roasting with coke in a furnace. - The more difficult (e.g. aluminium and sodium compounds) are decomposed by the electrolysis of aqueous solutions or molten compounds. In this sequence of decompositions, the energy needed becomes progressively higher moving from copper to aluminium, showing that the bonds in the aluminium compounds are stronger and so need more energy to break them than the bonds in the copper compounds. Increased Availability of Metals in Recent TimesAs our methods of metal extraction have become more sophisticated we have discovered more metals. There are many more metals available for us to use because of improved technology. For example, we did not know sodium or aluminium existed until we developed technology needed to carry out electrolysis (passage of an electric current through a solution or melted solid bring about a chemical change). Improvement of metallurgical skills for making and testing new alloys led to the incorporation of a wider range of metals into everyday products. This improvement led to increasing amount of alloys being produced. E.g. titanium wasnt widely used on its own but it was discovered that when Ti is combined with limited amounts of other metals, it improves various physical properties. Lower cost of electricity generation has also made it more attractive to extract metals requiring electrolysis. Two hundred years, the extraction technology was not as advanced (e.g. no electrolysis), meaning some metals like aluminium couldnt be extracted for use. Fifty years ago, electricity was much more expensive, discouraging the extraction of aluminium as it requires high amounts of electrical energy. Instead, steel was much more competitive and was used more. AlloyReasons for productionUses

Alnico

812% Al, 1526% Ni, 524% Co, up to 6% Cu, up to 1% Ti, and the balance is Fe.

Alnico alloys make strong permanent magnets, and can be magnetized to produce strong magnetic fields. They were produced to create a magnetic field upto three times that of the Earths. This phenomenon allowed scientists to use the alloy in many magnetic applications.

- Magnet applications - electric guitar pickups- microphones- sensors- loudspeakers - cow magnets

Magnalium

Aluminium with 5-50% Magnesium

It provides greater strength, greater resistant to corrosion and a lower density than pure aluminium. Also more workable and easier to wield than aluminium. However, too much magnesium e.g. >50% makes the alloy brittle and susceptible to corrosion.

- Pyrotechnics since when large amounts of Mg is present, the powder is flammable so used as a metal fuel.

- Aircraft and Vehicle components due to low density and high strength.

Vitallium

60% cobalt, 20% chromium, 5% molybdenum and other substances.

Developed by Albert W. Merrick in 1932.It has a very low in density, is lightweight and resists corrosion. Furthermore it is also a thermal resistor. Also does not react in the body with any substance like other metals do (inert). This makes it suitable for medical purpose

- Dentistry because it is lightweight and resists corrosion.- Medical surgery as the substance is inert to any body fluid under any condition.- Turbocharger components because of thermal resistance

Gunmetal

88% Copper, 10% Tin and 2% Zinc

It is very resistant to corrosion from water, steam and salt water. Its composition varies based on why it is produced but copper, tin and zinc are the three major components. Also withstands atmospheric corrosion.

- Guns- Valves, pump parts and steam fittings as it is resistant to corrosion from steam/salt water.- Machinery brushes- Gears and bearings subjected to heavy loads + low speeds.

Galinstan

68.5% Ga, 21.5% In, 10% Sn

Galinstan is commercially used as a mercury replacement due to its nontoxic properties. Has high reflectivity and lower density, and is produced as a regular replacement for mercury in astronomy.It is also a promising coolant, but is costly and aggressive, however ongoing experiments are being conducted.

- Thermometers due to its nontoxic properties, but inner tube must be coated with gallium oxide to prevent the alloy from wetting the glass surface.- Liquid mirror telescopes for astronomy -It is also a promising coolant.

Metals differ in their reactivity with other chemicals and this influences their usesReactions of metalsWe find that metals are not all different and can be grouped together on the basis of their chemical reactions. The reactions of metals with dilute acids, water and oxygen are most commonly considered. Metals vary in their reactions with certain substances. Some are very reactive whereas others are extremely unreactive to the same substance.In general: - metals that react vigorously with dilute acids also react vigorously with water and oxygen and are called active metals (e.g. Mg). - metals that react less vigorously with dilute acids also react less vigorously with water and oxygen are less active metals (e.g. Zn). Metals that do not react at all with dilute acids also do not react with water and oxygen and are called inactive metals (e.g. Au). Reaction with Oxygen Burning (combustion) is carried out by heating the metal in a Bunsen burner flame in air or oxygen. All metals except silver, platinum and gold react with oxygen to form oxides: - Li, Na, K, Ca, Ba react rapidly at room temperature. - Mg, Al, Fe, Zn react slowly at room temperature but burn vigorously if heated in air or pure oxygen. - Sn, Pb, Cu react slowly and only if heated. Those metals which burn in air or oxygen form crystalline white solids that have none of the physical properties of the original metal. When metals slowly react at room temperature, they lose their shiny lustrous appearance. Some, such as Al, become coated with a dull layer of tightly adhering oxide, preventing further reaction. Others like iron form a powdery surface layer of oxide that doesnt impede further reaction. Li, Na, K tarnish rapidly when exposed to air and must therefore be stored in liquid paraffin oil. Rubidium and caesium are so reactive that they catch fire in air and must be handled in an inert gas environment like argon. E.g. magnesium burns readily with a very bright flame to form a white solid. The reaction is magnesium + oxygen -> magnesium oxide 2Mg(s)+O2(g) 2MgO(s)Zinc burns slowly as a solid, but burns readily in powder form. 2Zn(s)+O2(g) 2ZnO(s)Iron reacts similarly to zinc4Fe(s)+3O2(g) 2Fe2O3(s)gold no reaction occurs. General word equation for the reaction of oxygen with metals is metal + oxygen metal oxide Reactions with water Most metals when placed in cold water undergo no observable changes and show no signs of chemical reaction:- Li, Na, K, Ca, Ba react with water at room temperature. - Mg, Al, Zn, Fe react with water at high temperatures. - Sn, Pb, Au, Ag, Cu dont react at all. When a reaction occurs with water the products formed are hydrogen gas and the metal hydroxide.metal + water metal hydroxide + hydrogen gasWhen calcium is dropped into water, bubbles of colourless gas form. Furthermore, a suspension of insoluble calcium hydroxide forms:calcium + water calcium hydroxide + hydrogen Ca(s) +2H2O(l) Ca (OH)2(s) + H2(g)

Magnesium no reaction with cold water but with hot water or steam, bubbles of gas are produced. Mg(s) + 2H2O(l) Mg(OH)2(aq) + H2(g)The formation of hydrogen in this reaction can be confirmed by collecting a sample of the gas produced and introducing a lighted splint. A small explosion or pop confirms the presence of hydrogen gas. An acid-base indicator such as phenolphthalein or litmus can be used to confirm the production of hydroxide ions. In the metal-water reaction, the metal displaces hydrogen from the water. The reaction involves the transfer of electrons from metal atoms to hydrogen atoms in the water and is classed as an oxidation-reduction reaction. The loss of electrons by metal atoms and the gain of electrons by hydrogen atoms can be represented by the following equations:Na(s) Na+(aq) + e2H2O(l) +2e- H2(g) + 2OH-(aq)Water is more energetically stable than dilute acids, thus less metals react with it in comparison to acid. Reactions with dilute acid Acids are substances, which in solution produce hydrogen ions, H+. It is the hydrogen ions which react with the metals. These ions result in the transfer of electrons between the substances involved. Most metals react with dilute hydrochloric and sulfuric acids to form hydrogen gas and a metal salt. metal + acid metal salt + hydrogen gasMagnesium vigorous bubbling from the surface of the metal, bubbles rise through the acid, the metal disappears and the container gets hot. The reaction observed is:magnesium + hydrochloric acid magnesium chloride + hydrogen Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g)Zinc a few bubbles are produced but the zinc doesnt disappear. The reaction that occurs is similar to the reaction with magnesium, with hydrogen being formed, but is slower and less vigorous. Zn(s)+2HCl(aq) ZnCl2(aq)+H2(g)With dilute sulfuric acid, similar reactions occur with magnesium and zinc, but the sulfate is formed instead of the chloride. Metals more reactive than magnesium, such as Na, K, Ca react explosively with dilute hydrochloric and sulfuric acids. Less reactive metals such as copper, silver and gold do not react with these acids. During the reaction between a metal and an acid, the metal dissolves as it loses electrons and forms positively charged ions. Hydrogen ions from the acid gain electrons to form hydrogen gas. As this reaction involves a transfer of electrons it is an oxidation-reduction reaction (redox reaction where reduction and oxidation occur simultaneously or electron-transfer reaction). The substance that loses one or more electrons has been oxidised. It is called a reducing agent. The substance that gains one or more electrons has been reduced. It is called an oxidant. Hence, two half equations can be written. Zinc: Ionic equation Zn(s) + 2H+(aq) Zn2+(aq) + H2(g)Half equations - Zn(s) Zn2+(aq) + 2e-2H+(aq) + 2e- H2(g) The zinc has been oxidised while the H+ has been reduced. Magnesium:Ionic equation Mg(s) + 2H+(aq) Mg2+ + H2(g) Half equations Mg(s) Mg2+(aq) + 2e-2H+(aq) + 2e- H2(g)The magnesium has been oxidised while the H+ has been reduced. Activity Series of Metals The different reactions of metals with dilute acids, water and oxygen can be used to draw up a list or sequence of the metals in order of decreasing reactivity. This is called the activity series of metals. In this list, metals that react most vigorously (e.g. Na) are placed at the top of the list, while metals that react least (e.g. Au) are placed at the bottom. Metals vary in their reactivity. The criteria used to place metals into an activity series is their ease of reaction with oxygen, water and acids. Reactive metals will react with oxygen, whereas those that are inactive will not, placing them lower on the activity series. A highly reactive metal will react with cold water, whereas metals that dont react with cold water may react with hot water and are lower on the activity series. Metals that dont react with water need to be tested in dilute acid to test their reactivity. Thus metals that react vigorously are deemed more reactive than those that react less vigorously or only with concentrated acids. The reason for this procedure is that a metals reactivity with acid is greater than its reactivity with water which is greater than its reactivity with oxygen. Thus by determining where each metal will react, we can draw an activity series.

Selection of Metals for Different Purposes Based on their Reactivity Copper is used for electrical appliances, telephone cables, radios, TVs, motors, roofing, plumbing because it will not react to oxygen or water. Calcium, an active metal, is used in the nuclear industry to convert uranium tetrafluoride to uranium. Lead, a relatively unreactive metal has low corrosion so it can be used in batteries, as solder and in lead foil. Silver, an unreactive metal, has very low corrosion so it is used in jewellery and coins, while its unstable salts are light sensitive and forms the basis of photography. Current and possible future developments in the use of metals The more recently discovered metals such as aluminium and magnesium are high in the activity series. These metals are finding more and more uses, especially in alloys. Aluminium is used in packaging, window frames, boats, cars and drink cans due to its strength, availability and lack of reactivity. Magnesium is used as a component in fireworks, military and emergency purposes and inside boilers due to its relatively high reactivity and since it burns bright when heated with air. Titanium is used as artificial joints, aircraft and ship bodies and pipes due to its low reactivity, stableness, resistance to corrosion and chemically inert nature in the human body. Zinc is used in galvanized roofs, fences, car bodies, motor vehicle grilles, and household appliances since it is fairly reactive, reacting with the environment as a sacrificial metal, protecting the less reactive metal such as iron. Due to golds resistance to corrosion it is being used in jewellery but also finding use in areas such as microchips and electronics. Relationship between the relative activities of metals and their positions in the Periodic TableBy inspecting our activity series it is possible to determine certain trends between them and the periodic table. The activity series shows that Group 1 metals are the most reactive, followed by Group 2 metals. Group 3 comes next in reactivity followed by some transition metals and then metals of group 4. At the end of the series are more transition metals (Cu, Ag, Pt, Au). The activity series also shows that in groups 1 and 2 reactivity increases from top to bottom. Hence, the reactivity of metals increase going down a group and decrease across a period from left to right. As metals and other elements were discovered, scientists recognised that patterns in their physical and chemical properties could be used to organize the elements into a periodic table. The reactions of metals with oxygen, water and dilute acids belong to a class of chemical reactions known as oxidation-reduction reactions. In each case, where a reaction occurs, the metal loses its valence electrons to form a positively charged ion. The relative ease with which a metal loses its valence electrons is a major factor affecting its reactivity. Very reactive metals such as potassium and sodium lose their valence electrons relatively easily. Less reactive metals such as copper dont lose their valence electrons as readily, and gold and silver rarely lose their electrons at all. First Ionisation energy is a measure of the energy needed to remove an electron from the electrostatic attractive force of the positively charged nucleus. The ionization energy of an atom or ion is defined as the amount of energy required to remove the most loosely bound electron from the atom or ion in the gaseous state. Ionisation energy is commonly measured in kJ/mol. The lower the ionisation energy, the easier it is to remove an electron. Therefore, the reactivity of metlas increases astheir ionisation energy decreases (transfer of electrons required in reactions).As we go from left ro right across the activity series, metal ions become easier to reduce to metal atoms. Due to the fact that metal ions are present in ores, it can be said that the further to the right in the activity series a metal is, the more easily it can be extracted from its ores.

Identify an appropriate model that has been developed to describe atomic structure The current model of the atomic structure is an adaptation of the original atomic structure outlined by Ernest Rutherford. In 1911, he suggested that the atom consisted of a small, dense core of positively charged particles in the centre (or nucleus) of the atom, surrounded by a swirling ring of electrons. He concluded through his experiments and the experiments of others that the nucleus was extremely dense (alpha particles would bounce off of it) but the electrons were extremely small, and spread out at large distances (alpha particles would pass right thorugh this area of the atom). Rutherfords atom resembled a tiny solar system with the positively charged nucleus always at the centre and the electrons reolvinvg around the nucleus. The positively charged particles in the nucleus of the atom were called protons. Protons carry an equal, but opposite, charge to electrons, but protons are much larger and heavier than electrons. Atoms are electrically neutral since the number of protons balances the number of electrons. However some essential refinemeents were necessary to this model and these were incorporated as they were discovered. For example, the discovery of neutrons in 1932 by James Chadwick explained why the dense nucleus of the atoms was able to stay together as it did. The discovery of subshells and valence electrons were essential and added to the same atomic structure proposed by Ernest Rutherford. It contained a number of errors, but provided scientists with a base that an atom is more than just a singular particle, and is made of protons, neutrons and electrons. Contributor

DateWhat was ContributedComment

Aristotle~330 BCFour Elements Fire, Air, Earth, Water

Antoine Lavoisier

~ 1770 - 1789Wrote the first list of the 33 elements currently known and also distinguished between metals and non-metalsSome of these elements were later found to be compound and mixtures.

Jns Jakob Berzelius1828Developed a table of atomic weights and also introduced letters to represent the elements rather than full names.

Johann Dbereiner

1829Developed groups of three elements known as triads. These elements had similar properties. Some examples of his triad include: Lithium, Sodium and Potassium formed a triad. Calcium, barium and Strontium formed a triad.Chlorine, bromine & iodine also formed a triad.He was the first man to bring forward the notion of groups. He proposed that nature contained triads of elements the middle element had properties that were an average of the other two members when ordered by the atomic weight. (Law of Triads)

Alexandre-Emile Bguyer de Chancourtois

1862Alexandre Bguyer de Chancourtoiswas the first person to list the known elements in order of increasing weight of their atoms. But due to the complicated nature of his proposed graph, his ideas were shrouded in less read journals. His graph was so complicated that most French experts still had trouble interpreting it. It was not until after Mendeleev that his work was credited.

JohnNewlands

1864At this stage over 60 elements were known to exist. Newlands arranged these elements in order of atomic weights and realised that the properties of the first and ninth elements, second and tenth elements etc. were very similar. Due to his he proposed the Law of Octaves which was simply that if the chemical elements are arranged according to increasing atomic weight, those with similar physical and chemical properties occur after each interval of seven elements. Newlands Law of Octaves identified that many of the elements had similarities but his law required similarities where none actually existed. However he was unable to comprehend that some elements had not been discovered and therefore did not leave any gaps for those elements. He was the first person to initiate the notion of periods.

Lothar Meyer

1869He was able to compile a periodic table containing 56 elements. He arranged the elements based on the periodicity of properties such as molar volume when it was arranged in the order of atomic weight. Meyers contribution was his ability recognises periodic behaviour. A repeating pattern of atomic volume. When atomic volume of an element was plotted against its atomic weight a clear pattern existed. Meyer realised that due to the graph, atomic volume rapidly peaks and then falls considerably.Dmitri Mendeleev and Lothar Meyer both produced their own Periodic tables at the same time, but Mendeleev is still considered to be the father of the Periodic table.

Meyer is also recognised for identifying periodic behaviour which allowed for the development of groups and periods.

Dmitri Mendeleev

1869He also produced a periodic table based on atomic weights like Lothar Meyer, but he arranged them periodically with elements that had similar properties arranged under each other. He also left certain gaps for elements that he believed had not been discovered yet. Furthermore, he was able to predict the properties of those elements. We know those elements to be gallium, scandium and germanium. Additionally, Mendeleev also re-arranged the order of the elements if their properties dictated it. For example: Tellurium is heavier than iodine but it comes before iodine in the periodic table.Periodic law properties of the elements vary periodically with their atomic weights The periodic law allowed for the properties of the elements to be estimated. Properties of the elements vary according to their atomic weights.

William Ramsay

1898He was able to discover the noble gases which allowed for the inclusion of six more elements into the periodic table. We know these gases are in their own separate group and are also highly unreactive.

In 1894 Ramsay removed oxygen, nitrogen, water and carbon dioxide from a sample of air and was left with a gas 19 times heavier than hydrogen, very unreactive and with an unknown emission spectrum. He called this gas Argon. In 1895 he discovered helium as a decay product of uranium and matched it to the emission spectrum of an unknown element in the sun that was discovered in 1868. He went on to discover neon, krypton and xenon, and realised these represented a new group in the Periodic Table. [footnoteRef:1] [1: ]

Henry Moseley

1914He was able to determine the atomic number of each of the elements discovered at the time. He was also able to modify the Periodic Law to ensure the properties of the elements vary periodically according to their atomic numbers.Modified periodic law properties of elements vary periodically with their atomic numbers Moseleys modified Periodic Law puts the some of the elements in the right order compared to what they were previously. For example, Argon and Potassium as well as Cobalt and Nickel were placed in their correct order.

Glenn Seaborg

1940He was able to discover and also synthesise elements that occurred after uranium in the periodic table, known as the lanthanides and actinides or the transuranic elements.

In 1940 uranium was bombarded with neutrons in a cyclotron to produced neptunium (Z=93). Plutonium (Z=94) was produced from uranium and deuterium. These new elements were part of a new block of the Periodic table called Actinides. Seaborg was awarded a Nobel Prize in 1951[footnoteRef:2]. [2: ]

Explain the relationship between the position of elemenetsi nthe Periodic Table, and:- electrical conductivity- ionisation energy- atomic radius - melting point- boiling point- combining power - electronegativity- reactivityReactivityThe reactivity of a metal associates well with its first ionisation energy: the lower the first ionisation energy, the greater the reactivity of the metal. This is due to one sole reason: that both reactivity of a metal and ionisation energy are related to the ease with which the metal will lose its electrons. Therefore the logical comparison can be made that:

For metallic elements reactivity decreases from left to right across a period of the table (for example Na, Mg, Al) and increases from top to bottom down a group (Be, Mg, Ca, Sr). [footnoteRef:3] [3: ]

This is simply because the more left and down you proceed in the periodic table, the easier it is for the electrons to be removed, thus resulting in higher reactivity. However, the case for non-metals is not as simple as it is for metals. This is mainly due to the fact that there are a minimum of two types of reactivity for non-metals. There is the formation of ions (anions) and also the formation of covalent compounds. Generally in both cases the reactivity increases as you go from left to right across a period. Furthermore, the reactivity decreases as you go from top to bottom down a group. This is simply because the farther to the right and up you proceed in the periodic table, the higher the electronegativity, this results in a more forceful exchange of electrons. Ionisation Energy First Ionisation Energy is the energy required to remove an electron from the outermost shell of an element when it is gaseous state. Ionisation energy is measure in kJ/mol. Each element has several ionisation energies and the energies always increase per ionisation level. This is simply because it requires more energy to remove a negative electron from a position ion than it does from a neutral species. This is fully due to the electrostatic attraction between the positive nucleus and the negative electron cloud. After the first electron is removed, there is extra electrostatic attraction on the remaining electrons making them harder to remove. Ionisation energies provide strong evidence towards periodic law. Furthermore they also provide significant confirmation that the atoms want to have noble gas configuration. As can be seen from the graph above, when first ionisation energies are plotted against atomic number a clear trend is seen. The minimum values are all captured by the alkali metals (group 1 Li, Na, K, Rb, and Cs) showing that it is easy to remove an electron from these elements. On the other hand the maximum values are captured by the noble gases (He, Ne, Ar, Kr, Xe, Rn) showing that a large amount of energy is needed to remove an electron from these stable elements. Elements with low ionisation energies readily form positive ions and therefore such elements form ionic compounds (Na+1, Ca+2, Al+3). [footnoteRef:4] [4: ]

As you go across any period of the periodic table, the first ionisation energy increases, indicating that when you move from left to right, the tendency to lose electrons deceases. When you go down any group of the periodic table, the ionisation energy decreases. This indicates that elements lose electrons less readily as we move from left to right. This is because elements on the right hand side of the periodic table wish to gain electrons to form an octet, whereas the ones on the left would rather lose those electrons. Also elements more readily lose electrons as we go down a group. This is because the increasing number of shells in the atom allow for the easier removal of the outermost electrons.Atomic Radius When atomic radius is plotted against atomic number, the curve shows a distinctly periodic nature. The atomic radius passes though a set of maximums which corresponding directly to the group 1 metals (also known as the alkali metals). There is also a set of minimums which occur in the last group of the periodic table known as the noble gases. Thus the relationship between the position of elements in the Periodic table and their atomic radius is that the atomic radius decreases from left to right across any period of the table. This is because of the stronger attractive forces in atoms between the opposite charges in the nucleus and electron cloud cause the atom to be contracted in slightly. Furthermore the atomic radius also increases in going down any group of the table. This is because of the increasing size of the nucleus as you move down a group. Also, new energy levels of electrons are added to the atom, each making the atom significantly larger in both mass and volume.Melting point When a substance melts, some of the forces that hold the particles together are broken or loosened so that the particles can move freely but are still together. The stronger the attraction forces (intermolecular bonds), the more energy is needed to break them, and thus they have higher melting points. When the melting points of the elements are plotted against their atomic numbers a periodic behaviour occurs, as the curve passes a series of minimums which correspond to the noble gases. The maximums do not appear in such a simple pattern however. The maximum melting points occur approximately half-way between the minimums.Boiling Point When a substance boils, the majority of the remaining attractive forces between the molecules (intermolecular forces) are broken so that the particles can freely and far apart (because of their gaseous state which results in rapid translational movement). The stronger the intermolecular bonds (attractive forces), the more energy is required to overcome them, thus giving them a higher boiling point. When the boiling points of the elements are plotted against atomic numbers, the graph that is produced is similar to the graph on the previous page which showed the melting points of the elements plotted against their atomic numbers. The boiling point graph undergoes a similar series of minimums which correspond to the atomic numbers of the noble gases. Furthermore, the maxima occur approximately half-way between the minimums.Electronegativity The electronegativity of an element is a measure of the ability of an atom of that element to attract bonding electrons towards itself when it forms compounds. If the difference in electronegativities of two elements is greater than 1.5, the elements will form an ionic compound; otherwise the compound will be covalent. [footnoteRef:5] [5: ]

The electronegativity increases as we move from left to right across a period. This is because elements situated on the left of the table have one or two valence electrons and would give those electrons away to achieve an octet. Accordingly, they have a low electronegativity. On the other hand, elements situated on the right of the table only require a few electrons to complete a full octet, so they want to grab other elements electrons, thus giving those elements high electro-negativity. The electronegativity deceases as we move down a group. This is because electrons situated at the top of the able have minimal electrons that they want to preserve. Thus they have a stronger desire to acquire more electrons. Elements situated on the bottom of the table have a large amount of electrons and therefore losing some is not an issue. This is mainly due to the electron shells. Electrons in the outer electron shells are not as tightly bound to the atom and are thus easily lost, whereas internal electrons (those closer to the nucleus) have much more electrostatic attraction and are thus tightly bound.Combining power (valency) The most common valency of an element is its group number (if it is in groups one to four) or eight minus its group number (if it is groups five to seven). The noble gases are situated in group eight (also known as group eighteen or group zero) because they have no valence electrons and therefore are very unreactive and rarely form compounds. It is not possible to determine some of the valencies of the elements situated outside the general groups (one to eight). These elements are known as the transition metals and have varying valencies. For example copper may have a valency of one or two, iron may have a valency of two or three, chromium may have a valency of two or three etc. However most of these transition elements from cations with a positive two charge. The position of an element determines its valency which hence determines its combining power. If an element is situated in group eight it has zero valencies and thus will have limited combining power. If an element is situated in any other group of the periodic table it will have a number of valence electrons meaning that it will have a significant combining power. Generally the most reactive metals are located to the bottom left of the periodic table (due to their low electronegativity) whereas the most reactive non-metals are situated towards the top-right (due to their high electronegativity). These elements have the greatest combining power but the lowest valencies. I.e. therefore it could be said that the lower the valency the greater the combining power.

Electric Conductivity Metals are good conductors of electricity, non-metals are not good conductors of electricity rather they are electrical insulators. This means that all the elements situated on left hand side of the periodic table (except hydrogen) all the way to group three have good electrical conductivity. This is mainly because of their metallic nature and structure. (I.e. they have metallic bonding which means there is a sea of delocalised electrons which can move freely and this allows for the conduction of electricity). The elements on the right hand side of the periodic table (the non-metals) are electrical insulators because they do not have free moving electrons. They usually form diatomic covalent bonds and this means that the electrons are tightly bound within the molecules and therefore no electricity can be conducted since no free electrons. This is with the exception of carbon, which despite being classified as a non-metal displays excellent electricity conductivity when in the form of graphite. All semi-metals are able to conduct electricity but Silicon, Germanium, Boron Tellurium which display high levels of resistance when it comes to electrical conductivity. Define the terms mineral and ore with reference to economic and non-economic deposits of natural resources. A naturally occurring, homogenous inorganic solid substance having a specific chemical composition and characteristic crystallic structure is considered a mineral, regardless of whether the substance is economical or non-economical to mine. An ore is a mineral or rock from which a valuable constituent, especially metals, can be economically and profitably extracted. Describe the relationship between the commercial prices of common metals, their actual abundance and relative cost of production. The commercial price of a metal is determined by these factors: - abundance of ores containing the metal- cost of the metals production from its ore- demand for the metal. For example, golds high price is due to its low abundance and high demand. However, it is relatively easy and cheap to produce. Although aluminium is the most abundant metal, the cost of production is high because the extraction process is difficult and requires the use of a high amount of electrical energy. This is why aluminium has historically been very expensive and is currently more expensive than many other commonly used metals such as iron, which is easily extracted, from its ore. Explain why ores are non-renewable resources. A renewable resource is any natural resource that can replenish itself naturally over time, like solar energy. However, when ores are dug up, they do not grow back and replenish itself over time. Therefore, ores are considered non-renewable resources.Describe the separation processes, chemical reactions and energy considerations involved in the extraction of copper from one of its ores. Extraction of copper from chalcopyrite (CuFeS2) occurs using both physical and chemical processes such as mining and crushing, froth flotation, roasting, smelting and electrolytic refining.1. Physical Separation from Rock Copper ore contains 2% or less copper and the rest is unwanted rock. The copper ore is separated from surrounding rock by digging or blasting. To help separate the mineral copper from gangue, the rock bearing chalcopyrite is crushed into very small pieces and ground into a powder in a ball mill.2. Froth Flotation A collector oil, such as organic xanthate or thiophosphate is added to the powder ore and adheres strongly to the chalcopyrite particles making them water repellent. However, this collector oil doesnt adsorb as strongly on other minerals like silicate minerals. These particles will not repel water. The mixture is placed into a water bath containing a foaming agent such as crude cresol or pine oil. Jets of air are forced through the water bath. Water repellent chalcopyrite particles stick to the foam bubbles and float to the surface making a froth. Meanwhile, gangue falls to the bottom and is removed and transported for further processing. The froth which contains the copper is skimmed off the surface and is taken away for roasting. The water bath mixture is recycled. Concentrating the ore by froth flotation can result in ores with up to 35% copper and a number of impurities such as lead, antimony and arsenic. 3. Roasting Roasting reduces impurities in the copper ore and produces calcine. Concentrated ore is heated to between 500C and 700C in air. Impurities in the ore, such as arsenic and antimony are oxidised and form volatile gases which can be removed. 4As(s) + 3O2(g) 2As2O3(g)4Sb(s) + 3O2(g) 2Sb2O3(g) Roasting the ore containing chalcopyrite also produces sulphur dioxide gas and a mixture of compounds called calcine. One of the reactions in the formation of calcine is show below:2CuFeS2(s)+4O2(g)2FeO(s)+ Cu2S(s)+3SO2(g)chalcopyrite+oxygencalcine+sulfur dioxide Calcine, a mixture of solids including copper oxides, sulphides and sulfates can then be smelted. 4. Smelting with Fluxes In this process, calcine is converted into matte (a mixture of copper sulphides and iron sulphides) Calcine is heated to over 1200C with fluxes such as silica (SiO2) and limestone (CaCO3) and calcine melts. Its compounds react with the fluxes. Any copper (I) oxide present is converted into copper (I) sulphide during the smelting. Cu2O(s) + FeS(s) Cu2S(l) + FeO(l) Impurities form a slag that floats on the surface and can be easily removed. One of the reactions to remove iron impurities is shown below:FeO(s)+SiO2(s)FeO.SiO2(l)

iron impurity+silicaslag

After the slag is removed, the product, called matte, is a mixture of copper sulphides (mostly Cu2S) and impurities such as iron sulphides. 5. Conversion of Matte into Blister Copper The matte contains about 40% copper and can be fed to a converter. Air is blown through molten matte which converts iron (II) sulphide to iron(II) oxide and sulphur dioxide. The iron(II) oxide reacts with silica to form slag. 2FeS(l) + 3O2(g) 2FeO(l) + 2SO2(g)2FeO(l) + SiO2(l) 2FeO.SiO2(l)Slag is skimmed off. Relatively pure copper(I) sulphide, Cu2S, accumulates at the bottom of the converter. Air is blasted through this copper(I) sulphide to reduce the copper and oxidise the sulphur to sulphur dioxideCu2S(l)+O2(g)2Cu(l)+SO2(g)

The impure copper produced by the converter is called blister copper since bubbles of sulphur dioxide gas on the surface of the copper look like blisters. Blister copper contains 97-98% copper. Impurities in blister copper can include Au, Ag, Sn, Ni, S, Te, Zn, Pb, Fe

6. Electrorefining The copper is refined by electrolysis. Thin pure starter sheet cathodes (thin copper foil) and a series of impure copper anodes are suspended in a tank. Oxidation occurs at the anode and reduction occurs at the cathode, forming a pure layer of copper at the cathode. Copper ions transfer from the impure anode and forms pure copper at the cathode. The anode disintegrates. The concentration of copper ions in the electrolyte remains constant. For every copper ion produced at the anode, a copper ion is reduced to metallic copper at the cathode. A slime at the bottom of the tank is formed containing valuable metals which are less active than copper. They occur below copper in the table of standard electrode potentials, so they are weaker redundants than copper and will not be oxidised at the anode. Impurities are left behind in the solution which are more active than copper. Lead occurs above copper in the table of standard reduction potentials, so lead is a stronger redundant than copper and will be oxidised at the anode. Pb(s) Pb2+(aq)+ 2e-However, lead forms an insoluble precipitate with the sulfate ions in the electrolyte:Pb2+(aq)+ SO42-(aq) PbSO4(s)PbSO4(s)will be found in the slime at the bottom of the tank. The electrolyte is an aqueous solution of 3-4% copper sulphate and 10-16% sulphuric acid. A current at a potential energy of 0.2-0.4 V is required. It contains copper ions flowing through the tank. The external power supply is used to pull electrons out of the anode and push them to the cathode. Anode:Cu(s) Cu2+(aq) + 2e-Cathode:Cu2+(aq) + 2e- Cu(s) Overall reaction: Cu(s)+Cu2+(aq)Cu2+(aq)+Cu(s)

This produces a copper that is 99.99% pure. Energy Considerations Input of energy is required throughout most of the production process to extract the pure copper from chalcopyrite and this adds significantly to the energy costs. Electrorefining requires large amounts of electrical energy. Therefore factors such as placing the refinery in a location where cheap electricity is available need to be considered. Significant amounts of coal are used in the smelting and the cost of acquiring, storing and transporting coal must be considered throughout the process. The combustion of coal in the roasting stage generates heat energy for the various reactions involving the conversion of copper minerals into copper. Energy is required in operating the mine machinery and ball mills and during froth flotation and purification processes. Although the reduction of most metal ores is endothermic, some energy is released in the copper-smelting reactions. The total amount of energy required is factored into the commercial price of copper so that profit is made. Producing 1 tonne of copper requires a total of energy in the order of 105 MJ, 2-3 times less than that of aluminium. Recount the steps taken to recycle aluminiumCollection and Transportation Aluminium products, such as drink cans and car parts, are collected through council initiatives as well as through the work of individuals and organisations. Material transported to the central processing plant.Sorting and Separation Although aluminium doesnt contain magnetic properties, steel does, so steel is removed by using magnetic separation. To ensure alloys of aluminium remain constant, used aluminium cans are separated from other aluminium products. Preparation Aluminium products are compressed to form bales (a separate bale is used for aluminium cans) and then further processed. Remelting and Refining Baled aluminium is fed into a rotary furnace which reaches temperatures of 780C, melting the aluminium. . Molten aluminium is cast into ingots, which are sent to rolling mills to create new kitchenware, drink cans, foil and other products made from aluminium. Aluminium Cans Aluminium cans are gathered at large, regional scrap processing companies. Here, the cans are condensed into highly dense briquettes or bales, which are shipped off to aluminium companies for melting. At the aluminium company, the condensed cans are shredded, crushed and stripped of their inside and outside decorations via a burning process and then melted in a furnace. The molten aluminium is treated to remove impurities and is then poured into casting units. The aluminium ingot solidifies gradually, in three hours, to produce 18 tonne ingots. The ingots are fed into rolling mills which reduce the thickness of the metal. The metal is coiled and shipped to can makers, who deliver cans to beverage companies for filling. Discuss the importance of predicting yield in the identification, mining, and extraction of commercial ore deposits. Yield may be considered as the amount of metal mined in one tonne of ore or the total quantity of product the mine will produce in its estimated life. By predicting yield, the amount of mineral and profit expected to be returned from each ore can be determined. Without being able to predict the yield of an ore deposit, there is no way to know if it will be a profitable investment. Mining costs a lot of money and hence, no one will invest in equipment and infrastructure without knowing what quantities of ore is going to be produced and how long production is going to last. Predicting the yield allows the mining company to estimate the costs it is going to take to process the metal, to see if it is economically viable. Predicting the yield allows the mining company to select the extraction method which creates the most product for the cheapest price. A prediction of the yield allows the mining company to choose the location of extraction facility in order to maximise financial return. For example, a commercial ore deposit with a high yield means a large amount of mineral will be produced, and therefore it is more economically viable to have the extraction facility close to consumers or the refinery to save transport costs. This is not great an issue for deposits with lower yield, as transportation costs are already low. Justify the increased use of recycling of metals in our society and across the world. Since metals are non-renewable resources, reserves in Earths crust will become harder to find and extract, increasing costs, and it is possible to run out of these metals if not recycled. Recycling metals is frequently more energy efficient and less polluting than extracting metals. For example, energy consumption when recycling aluminium is about 10% of the energy needed to extract it from bauxite and carbon emissions are about 5% as much. Recycling metal conserves energy that would otherwise be expended in drilling ore, refining the metal and other processes of the metal manufacturing process. Energy conservation levels vary according to the product type. Recycling aluminum uses 95 percent less energy than deriving it from raw materials, while recycling steel saves 60 percent. Recycling metals creates 36 times more jobs than sending the same amount of metal waste to the incinerator and six times more than sending the metal to a landfill. Recycling metals creates many jobs and is positive for the economy. Extraction of metals produces greenhouse gases (through the burning of fossil fuels for energy) and recycling eliminates the emission of these gases, combating global warming. These greenhouse gas emissions may also cause harmful levels of air pollution in cities, resulting in potential respiratory problems. Recycling consumes 40% less water than extracting metals from the ore. Extracting metals is unsustainable since energy used is produced by non-renewable resources such as coal. A limited amount of metal ore is in the planet. Metal recycling conserves natural resources and reduces the amount of virgin ore needed to be mined by providing manufacturers with a source of already-mined metal. For example, recycling a tonne of aluminium conserves up to 8 tonnes of bauxite ore and 14 megawatt hours of electricity. Recycling produces no waste, whereas extraction produces tailings and other waste, which must stored in landfills. Many metals are generally mined using an opencast system which disrupts the ecological processes of the land and causes habitat destruction and land degradation. A majority of the benefits affect nations worldwide and hence recycling is promoted in all countries across the globe to ensure environmental sustainability to the worlds resources. Analyse information to compare the cost and energy expenditure involved in the extraction of aluminium from its ore and the recycling of aluminium.ExtractionCost Land must be purchased, which costs millions of dollars. Transportation expensive for ores to be transported from the mine to the refinery Waste is expensive to dispose of. For example, Fe2O3 is formed during the refining process and must be transported and dumped into disposal ponds. 10 tonnes of bauxite are required to produce 1 tonne of aluminium using this process Bayer Process used to convert bauxite to alumina (Al2O3) requires large amounts of chemicals such as sodium hydroxide, which must be purchased and is additional cost to extraction. Opencast mining, which involves the removal of all topsoil and vegetation and soil beneath is an expensive method as it requires expensive machinery and many hours of labour. 35% of the total cost from producing aluminium comes from the high amount of electricity used during electrolysis.Energy Bayer Process (refining of bauxite to produce alumina) requires 15 000 MJ of energy per tonne. Electrolytic reduction (refining of alumina to produce aluminium) requires 100 000 amps per tonne. Refineries and smelting factories often require their own power plant, due to the large amounts of energy that they require. Total energy 50 000 MJ per tonne (14000 kWH) RecyclingCost Minimal transportation costs, compared with the extraction method. Less machinery required. Inputs (used cans and other aluminium products) are free, whereas the extraction method requires land to be purchased. No chemicals have to be purchased. Costs much lower since very little electrical energy is used in comparison to extracting aluminium. Energy Requires 5% of energy used for extraction approximately 19 times less energy used. Only energy required is used to heat and melt the aluminium, which in comparison to the large amounts of energy used in the many processes involved with the extraction method, is a minimal amount. Total energy 2500 MJ (700 kWH)Overview Recycling aluminium is a superior alternative to raw extraction, as a means of producing aluminium for use in society. This is attributable to the lower costs and energy required to recycle aluminium, hence ensuring its sustainability and limiting its impact upon the environment.