Periodic table 1

Periodic tableThe periodic table of the chemical elements (also known as the periodic table or periodic table of the elements)is a tabular display of the 118 known chemical elements organized by selected properties of their atomic structures.Elements are presented by increasing atomic number, the number of protons in an atom's atomic nucleus. Whilerectangular in general outline, gaps are included in the horizontal rows (known as periods) as needed to keepelements with similar properties together in vertical columns (known as groups), e.g. alkali metals, alkali earths,halogens, noble gases.[1]

The following is the periodic table as defined by the IUPAC:

Group # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Period

1 1H

2He

2 3Li

4Be

5B

6C

7N

8O

9F

10Ne

3 11Na

12Mg

13Al

14Si

15P

16S

17Cl

18Ar

4 19K

20Ca

21Sc

22Ti

23V

24Cr

25Mn

26Fe

27Co

28Ni

29Cu

30Zn

31Ga

32Ge

33As

34Se

35Br

36Kr

5 37Rb

38Sr

39Y

40Zr

41Nb

42Mo

43Tc

44Ru

45Rh

46Pd

47Ag

48Cd

49In

50Sn

51Sb

52Te

53I

54Xe

6 55Cs

56Ba

*lanthanides

72Hf

73Ta

74W

75Re

76Os

77Ir

78Pt

79Au

80Hg

81Tl

82Pb

83Bi

84Po

85At

86Rn

7 87Fr

88Ra

**actinides

104Rf

105Db

106Sg

107Bh

108Hs

109Mt

110Ds

111Rg

112Cn

113Uut

114Uuq

115Uup

116Uuh

117Uus

118Uuo

* Lanthanides (Lanthanoids) 57La

58Ce

59Pr

60Nd

61Pm

62Sm

63Eu

64Gd

65Tb

66Dy

67Ho

68Er

69Tm

70Yb

71Lu

** Actinides (Actinoids) 89Ac

90Th

91Pa

92U

93Np

94Pu

95Am

96Cm

97Bk

98Cf

99Es

100Fm

101Md

102No

103Lr

This common arrangement of the periodic table separates the lanthanides (lanthanoids) and actinides (actinoids) (thef-block) from other elements. The wide periodic table incorporates the f-block. The extended periodic table adds the8th and 9th periods, incorporating the f-block and adding the theoretical g-block.

Element categories in the periodic table

Metals Metalloids Nonmetals UnknownchemicalpropertiesAlkali

metalsAlkaline

earthmetals

Inner transition metals Transitionmetals

Post-transitionmetals

Othernonmetals

Halogens Noblegases

Lanthanides Actinides

Solids Liquids Gases Unknown Primordial From decay Synthetic

Although there were precursors, the current presentation's invention is generally credited to Russian chemist Dmitri Mendeleev, who developed a version of the now-familiar tabular presentation in 1869 to illustrate recurring ("periodic") trends in the properties of the then-known elements.[2] The layout of the table has been refined and

Periodic table 2

extended over time, as new elements have been discovered, and new theoretical models have been developed toexplain chemical behavior.[3]

Since the periodic table accurately predicts the abilities of various elements to combine into chemical compounds,use of the periodic table is now ubiquitous within the academic discipline of chemistry, providing a usefulframework to classify, systematize, and compare many of the many different forms of chemical behavior. The tablehas found many applications not only in chemistry and physics, but also in such diverse fields as geology, biology,materials science, engineering, agriculture, medicine, nutrition, environmental health, and astronomy. Its principlesare especially important in chemical engineering.One of the strengths of Mendeleev's presentation is that the original version accurately predicted of the properties ofthen-undiscovered elements expected to fill gaps in his arrangement. For example: "eka-aluminium", expected tohave properties intermediate between aluminium and indium, was discovered with said properties in 1875 andnamed gallium. No gaps remain in the current 118-element periodic table; all elements from hydrogen to plutoniumexcept technetium, promethium and neptunium exist in the Earth in macroscopic or recurrently produced tracequantities. The three said exceptions do exist naturally, but only in trace amounts as the result of rare nuclearprocesses from decay of heavy elements. Every element through Copernicium, element 112, has been isolated,characterized, and named, and elements 113 through 118 have been synthesized in laboratories around the world.While plutonium is now included among the 91 regularly occurring natural elements, and technetium, promethium,and neptunium also occur naturally in transient trace amounts, these four elements were first identified andcharacterized from technologically produced samples. Numerous synthetic radionuclides of various naturallyoccurring elements have been produced as well.Production of additional synthetic elements beyond atomic number 118 is being pursued; whether the next elementswill neatly fill an eighth period or require modifications to the overall patterns of the present periodic table remainsunknown.

Organizing principlesThe main value of the periodic table is the ability to predict the chemical properties of an element based on itslocation on the table. It should be noted that the properties vary differently when moving vertically along thecolumns of the table than when moving horizontally along the rows.[1]

The layout of the periodic table demonstrates recurring ("periodic") chemical properties. Elements are listed in orderof increasing atomic number (i.e., the number of protons in the atomic nucleus). Rows are arranged so that elementswith similar properties fall into the same columns (groups or families). According to quantum mechanical theories ofelectron configuration within atoms, each row (period) in the table corresponded to the filling of a quantum shell ofelectrons. There are progressively longer periods further down the table, grouping the elements into s-, p-, d- andf-blocks to reflect their electron configuration.[1]

Elements, natural and syntheticOnly chemical elements, not mixtures, compounds, or subatomic particles, are included in the periodic table. Eachelement has a single entry, even if it has multiple isotopes.[1]

As of June 2011, the periodic table includes 118 chemical elements whose discoveries have been confirmed. Of these, 91 are regularly occurring primordial or recurrently produced elements found naturally on the Earth, at least in transient trace amounts, and three others occur naturally, but only incidentally.[1] The 24 other known elements (those from americium through ununoctium) are synthetic, produced by human technology but not regularly or incidentally occurring naturally.[1] Various synthetic elements, as well as synthetic isotopes of naturally occurring elements, are now also present in the environment from such sources as nuclear weapons explosions, nuclear waste processing, and disposal of materials including industrial and medical nucleotides. For example, americium and its

Periodic table 3

decay product neptunium are incidentally present in household and commercial waste from disposal of unwantedamericium-containing smoke detectors.Formal naming of the chemical elements is overseen by the International Union of Pure and Applied Chemistry(IUPAC). Provisional names, such as ununtrium, ununquadium, or ununpentium, are provided for elements that havebeen discovered but not yet been formally named; these names are based on the three digits of their atomicnumbers.[1] [4]

Atomic numberBy definition, each chemical element has a unique atomic number, the number of protons in its nucleus. Differentatoms of many elements have different numbers of neutrons, which differentiates between isotopes of an element.For example, all atoms of hydrogen have one proton, and no atoms of any other element have exactly one proton. Onthe other hand, a hydrogen atom can have one or two neutrons in its nucleus, or none at all, yet all of these cases areisotopes of hydrogen, not instances of some other element. (A hydrogen atom with no neutrons in addition to its soleproton is called protium, one with one neutron in addition to its proton is called deuterium, and one with twoadditional neutrons, tritium.)In the modern periodic table, the elements are placed progressively in each row (period) from left to right in thesequence of their atomic numbers, with each new row starting with the next atomic number following the lastnumber in the previous row. No gaps or duplications exist. Since the elements can be uniquely sequenced by atomicnumber, conventionally from lowest to hightest, sets of elements are sometimes specified by such notation as"through", "beyond", or "from ... through", as in "through iron", "beyond uranium", or "from lanthanum throughlutetium". The terms "light" and "heavy" are sometimes also used informally to indicate relative atomic numbers (notdensities!), as in "lighter than carbon" or "heavier than lead", although technically the weight or mass of atoms of anelement (their atomic weights or atomic masses) do not always increase monotonically with their atomic numbers.The significance of atomic numbers to the organization of the periodic table was not appreciated until the existenceand properties of protons and neutrons became understood. Mendeleev's periodic tables instead used atomic weights,information determinable to fair precision in his time, which worked well enough in most cases to give a powerfullypredictive presentation far better than any other comprehensive portrayal of the chemical elements' properties thenpossible. Substitution of atomic numbers, once understood, gave a definitive, integer-based sequence for theelements, still used today even as new synthetic elements are being produced and studied.

Periodicity of chemical propertiesThe primary determinant of an element's chemical properties is its electron configuration, particularly the valenceshell electrons. For instance, any atoms with four valence electrons occupying p orbitals will exhibit some similarity.The type of orbital in which the atom's outermost electrons reside determines the "block" to which it belongs. Thenumber of valence shell electrons determines the family, or group, to which the element belongs.[1]

Periodic table 4

Subshell S G F D P

Period

1 1s

2 2s 2p

3 3s 3p

4 4s 3d 4p

5 5s 4d 5p

6 6s 4f 5d 6p

7 7s 5f 6d 7p

8 8s 5g 6f 7d 8p

The total number of electron shells an atom has determines the period to which it belongs. Each shell is divided intodifferent subshells, which as atomic number increases are filled in roughly this order (the Aufbau principle) (seetable).[5] Hence the structure of the periodic table. Since the outermost electrons determine chemical properties,those with the same number of valence electrons are generally grouped together.[1]

Progressing through a group from lightest element to heaviest element, the outer-shell electrons (those most readilyaccessible for participation in chemical reactions) are all in the same type of orbital, with a similar shape, but withincreasingly higher energy and average distance from the nucleus. For instance, the outer-shell (or "valence")electrons of the first group, headed by hydrogen, all have one electron in an s orbital. In hydrogen, that s orbital is inthe lowest possible energy state of any atom, the first-shell orbital (and represented by hydrogen's position in the firstperiod of the table).[6] In francium, the heaviest element of the group, the outer-shell electron is in the seventh-shellorbital, significantly further out on average from the nucleus than those electrons filling all the shells below it inenergy. As another example, both carbon and lead have four electrons in their outer shell orbitals.[1]

Note that as atomic number (i.e., charge on the atomic nucleus) increases, this leads to greater spin-orbit couplingbetween the nucleus and the electrons, reducing the validity of the quantum mechanical orbital approximation model,which considers each atomic orbital as a separate entity.

Groups

A group or family is a vertical column in the periodic table. Groups are considered the most important method ofclassifying the elements. In some groups, the elements have very similar properties and exhibit a clear trend inproperties down the group. Under the international naming system, the groups are numbered numerically 1 through18 from the left most column (the alkali metals) to the right most column (the noble gases).[7] The older namingsystems differed slightly between Europe and America (the table shown in this section shows the old AmericanNaming System).[8]

Some of these groups have been given trivial (unsystematic) names, such as the alkali metals, alkaline earth metals,halogens, pnictogens, chalcogens, and noble gases. However, some other groups, such as group 7, have no trivialnames and are referred to simply by their group numbers, since they display fewer similarities and/or verticaltrends.[7]

Modern quantum mechanical theories of atomic structure explain group trends by proposing that elements within thesame group generally have the same electron configurations in their valence shell, which is the most important factorin accounting for their similar properties.[1]

Elements in the same group show patterns in atomic radius, ionization energy, and electronegativity. From top to bottom in a group, the atomic radii of the elements increase. Since there are more filled energy levels, valence electrons are found farther from the nucleus. From the top, each successive element has a lower ionization energy

Periodic table 5

because it is easier to remove an electron since the atoms are less tightly bound. Similarly, a group has a top tobottom decrease in electronegativity due to an increasing distance between valence electrons and the nucleus.[9]

Periods

A period is a horizontal row in the periodic table. Although groups are the most common way of classifyingelements, there are some regions of the periodic table where the horizontal trends and similarities in properties aremore significant than vertical group trends. This can be true in the d-block (or "transition metals"), and especially forthe f-block, where the lanthanides and actinides form two substantial horizontal series of elements.

Periodic trend for ionization energy. Each period begins at a minimum for the alkalimetals, and ends at a maximum for the noble gases.

Elements in the same period showtrends in atomic radius, ionizationenergy, electron affinity, andelectronegativity. Moving left to rightacross a period, atomic radius usuallydecreases. This occurs because eachsuccessive element has an addedproton and electron which causes theelectron to be drawn closer to thenucleus.[10] This decrease in atomicradius also causes the ionizationenergy to increase when moving fromleft to right across a period. The moretightly bound an element is, the more energy is required to remove an electron. Electronegativity increases in thesame manner as ionization energy because of the pull exerted on the electrons by the nucleus.[9] Electron affinityalso shows a slight trend across a period. Metals (left side of a period) generally have a lower electron affinity thannonmetals (right side of a period) with the exception of the noble gases.[11]

Blocks

This diagram shows the periodic table blocks with the CAS (American Group NumberingSystem).

Because of the importance of theoutermost electron shell, the differentregions of the periodic table aresometimes referred to as periodic tableblocks, named according to thesubshell in which the "last" electronresides. The s-block comprises the firsttwo groups (alkali metals and alkalineearth metals) as well as hydrogen andhelium. The p-block comprises the lastsix groups which are groups 13through 18 in IUPAC (3A through 8Ain American) and contains, amongothers, all of the semimetals. Thed-block comprises groups 3 through 12in IUPAC (or 3A through 8A inAmerican group numbering) and contains all of the transition metals. The f-block, usually offset below the rest of theperiodic table, comprises the lanthanides and actinides.[12]

Periodic table 6

Uncertainties after element 118

Element 118 completes the seventh period of the periodic table. Since the properties of any additional elements arestill unknown, it is unclear whether they will continue the pattern of the currently accepted periodic table as anadditional period (Period 8), or require further adaptations or adjustments to the currently known patterns. Glenn T.Seaborg expected the next 50 elements to form an eighth period, including a two-element s-block for elements 119and 120, a g-block (the first) for the next 18 elements (121-138), filling a g-shell of electrons, and the 30 additionalelements continuing the current p-, d-, and f-blocks.[13] [14] However, some physicists, including Pekka Pyykkö, havetheorized that these additional elements will deviate from the Madelung energy-ordering rule, which predicts howelectron shells are filled, and thus affect the appearance of the present periodic table.[15]

Conventional and alternative formats

The periodic table as commonly presented, with horizontal periods, vertical groups, andhighlighting to show similar elements. Rather than being incorporated in their proper

places, the lanthanides and actinides are here shown in separate rows beneath the otherelements, providing a more convenient (and aesthetically more pleasing), but less

accurate, layout.

In printed or other formally presentedperiodic tables, each element isprovided a formatted cell that providesselected information on each element.Atomic number, element symbol, andname, are generally included, as wellas selected other information, such aseach element's atomic weight, density,melting and boiling points, crystalstructure as a solid, origin, abbreviatedelectron configuration,electronegativity, and most commonvalence numbers.[16]

The information included in a periodictable can be presented in many ways,including selection of kinds of data tobe shown, layout within the cells representing particular elements, and the format used to present the table's periodicpatterns. Colors, symbols, and other formatting conventions are often used in periodic tables to show selectedadditional information for each element compactly. Interactive versions may also include hyperlinks to additionalinformation, as in the version shown at the top of this Wikipedia article.

Periodic table 7

Sculpture of the periodic table in circular layout, with the portrait of DmitriMendeleev in the middle (Bratislava, Slovakia). The table is shown to be almost

circular even though most commonly it is not drawn so.

While the iconic format presented above iswidely used,[1] other alternative periodictables exist, including not only variousrectangular formats, but also circular orcylindrical versions in which the rows(periods) flow from one into another,without the arbitrary breaks required at themargins of the usual printed orscreen-formatted versions.

In presentations of the periodic table, thelanthanides and the actinides arecustomarily shown as two additional rowsbelow the main body of the table,[1] withplaceholders or else a selected singleelement of each series (either lanthanum orlutetium, and either actinium or lawrencium,respectively) shown in a single cell of themain table, between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely amatter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the lanthanide andactinide series in their proper places, as parts of the table's sixth and seventh rows (periods).

Many presentations of the periodic table show a dark stair-step diagonal line along the metalloids, with metals to theleft of the line and non-metals to the right.[1] [17] Various other groupings of the chemical elements are sometimesalso highlighted on a periodic table, such as transition metals, poor metals, and metalloids. Other informal groupingsof the elements exist, such as the platinum group and the noble metals, but are rarely addressed in periodic tables.

Hydrogen is usually placed above lithium, although its chemistry differs substantially from that of lithium and theother alkali metals; some periodic tables place it on its own.[1]

Elements with atomic numbers greater than 82, as well as technetium and promethium, have no stable isotopes; theatomic mass of each of these element's isotope having the longest half-life is typically reported on periodic tableswith parentheses.[18]

Periodic table 8

History

Mendeleev's 1869 periodic table; note that his arrangement presents the periodsvertically, and the groups horizontally

In 1789, Antoine Lavoisier published a listof 33 chemical elements. Although Lavoisiergrouped the elements into gases, metals,non-metals, and earths, chemists spent thefollowing century searching for a moreprecise classification scheme. In 1829,Johann Wolfgang Döbereiner observed thatmany of the elements could be grouped intotriads (groups of three) based on theirchemical properties. Lithium, sodium, andpotassium, for example, were groupedtogether as being soft, reactive metals.Döbereiner also observed that, whenarranged by atomic weight, the secondmember of each triad was roughly theaverage of the first and the third.[19] Thisbecame known as the Law of Triads.[20]

German chemist Leopold Gmelin workedwith this system, and by 1843 he hadidentified ten triads, three groups of four,and one group of five. Jean Baptiste Dumaspublished work in 1857 describingrelationships between various groups ofmetals. Although various chemists were ableto identify relationships between small

groups of elements, they had yet to build one scheme that encompassed them all.[19]

German chemist August Kekulé had observed in 1858 that carbon has a tendency to bond with other elements in aratio of one to four. Methane, for example, has one carbon atom and four hydrogen atoms. This concept eventuallybecame known as valency. In 1864, fellow German chemist Julius Lothar Meyer published a table of the 49 knownelements arranged by valency. The table revealed that elements with similar properties often shared the samevalency.[21]

English chemist John Newlands produced a series of papers in 1864 and 1865 that described his own classificationof the elements: he noted that when listed in order of increasing atomic weight, similar physical and chemicalproperties recurred at intervals of eight, which he likened to the octaves of music.[22] [23] This Law of Octaves,however, was ridiculed by his contemporaries, and the Chemical Society refused to publish his work.[24]

Nonetheless, Newlands was able to draft an atomic table and use it to predict the existence of missing elements, suchas germanium. The Chemical Society only acknowledged the significance of his discoveries some five years afterthey credited Mendeleev.

Periodic table 9

Dmitri Mendeleev

Russian chemistry professor Dmitri Ivanovich Mendeleev and German chemistJulius Lothar Meyer independently published their periodic tables in 1869 and1870, respectively. They both constructed their tables in a similar manner: bylisting the elements in a row or column in order of atomic weight and starting anew row or column when the characteristics of the elements began to repeat.[25]

The success of Mendeleev's table came from two decisions he made: The firstwas to leave gaps in the table when it seemed that the corresponding element hadnot yet been discovered.[26] Mendeleev was not the first chemist to do so, but hewas the first to be recognized as using the trends in his periodic table to predictthe properties of those missing elements, such as gallium and germanium.[27] Thesecond decision was to occasionally ignore the order suggested by the atomicweights and switch adjacent elements, such as cobalt and nickel, to better classifythem into chemical families. With the development of theories of atomicstructure, it became apparent that Mendeleev had listed the elements in order of increasing atomic number.[28]

With the development of modern quantum mechanical theories of electron configurations within atoms, it becameapparent that each row (or period) in the table corresponded to the filling of a quantum shell of electrons. InMendeleev's original table, each period was the same length. However, because larger atoms have more electronsub-shells, modern tables have progressively longer periods further down the table.[29]

In the years following publication of Mendeleev's periodic table, the gaps he identified were filled as chemistsdiscovered additional naturally occurring elements. It is often stated that the last naturally occurring element to bediscovered was francium (referred to by Mendeleev as eka-caesium) in 1939.[30] However, plutonium, producedsynthetically in 1940, was identified in trace quantities as a naturally occurring primordial element in 1971.[31]

The production of various transuranic elements has expanded the periodic table significantly, the first of these beingneptunium, synthesized in 1939.[32] Because many of the transuranic elements are highly unstable and decayquickly, they are challenging to detect and characterize when produced, and there have been controversiesconcerning the acceptance of competing discovery claims for some elements, requiring independent review todetermine which party has priority, and hence naming rights. The most recently named element is copernicium(number 112), named on 19 February 2010;[33] the most recently accepted discoveries are ununquadium (114) andununhexium (116), both accepted on 1 June 2011.[34]

References[1] Gray, Theodore (2009). The Elements: A Visual Exploration of Every Known Atom in the Universe. New York: Black Dog & Leventhal

Publishers. pp. 240. ISBN 978-1-57912-814-2.[2] Dimitri Mendelejew: Ueber die Beziehungen der Eigenschaften zu den Atomgewichten der Elemente. In: Zeitschrift für Chemie. 1869, pp.

405–406.[3] IUPAC article on periodic table (http:/ / www. iupac. org/ didac/ Didac Eng/ Didac01/ Content/ S01. htm)[4] Koppenol, W. H. (2002). "Naming of New Elements (IUPAC Recommendations 2002)" (http:/ / media. iupac. org/ publications/ pac/ 2002/

pdf/ 7405x0787. pdf) (PDF). Pure and Applied Chemistry 74 (5): 787–791. .[5] Moore, p. 46[6] Hornback, Joseph (2006). Organic Chemistry (2nd ed.). Pacific Grove: Thomson Brooks/Cole. p. 62. ISBN 978-0-534-49317-2.

OCLC 66441248.[7] Leigh, G. J. Nomenclature of Inorganic Chemistry: Recommendations 1990. Blackwell Science, 1990. ISBN 0632024941.[8] Leigh, Jeffery. "Periodic Tables and IUPAC" (http:/ / www. iupac. org/ publications/ ci/ 2009/ 3101/ 1_leigh. html). Chemistry International:

The News Magazine of The International Union of Pure and Applied Chemistry (IUPAC). . Retrieved 23 March 2011.[9] Moore, p. 111[10] Mascetta, Joseph (2003). Chemistry The Easy Way (4th ed.). New York: Hauppauge. p. 50. ISBN 9780764119781. OCLC 52047235.[11] Kotz, John; Treichel, Paul; Townsend, John (2009). Chemistry and Chemical Reactivity, Volume 2 (7th ed.). Belmont: Thomson

Brooks/Cole. p. 324. ISBN 978-0-495-37812-1. OCLC 220756597.[12] Jones, Chris (2002). d- and f-block chemistry. New York: J. Wiley & Sons. p. 2. ISBN 9780471224761. OCLC 300468713.

Periodic table 10

[13] Seaborg, Glenn (August 26, 1996). "An Early History of LBNL" (http:/ / www. lbl. gov/ LBL-PID/ Nobelists/ Seaborg/ 65th-anniv/ 29.html). .

[14] Frazier, K. (1978). "Superheavy Elements". Science News 113 (15): 236–238. doi:10.2307/3963006. JSTOR 3963006.[15] "Extended elements: new periodic table" (http:/ / www. rsc. org/ Publishing/ ChemScience/ Volume/ 2010/ 11/ Extended_elements. asp).

2010. .[16] An example (among many) showing several of these descriptors: (Plasticized placemat) Painless Learning Placemats: Periodic Table of the

Elements. M. Ruskin Co.. 2000. pp. 2.[17] Science Standards of Learning Curriculum Framework (http:/ / www. doe. virginia. gov/ VDOE/ Instruction/ Science/ ScienceCF-PS. doc)[18] Dynamic periodic table (http:/ / www. ptable. com/ )[19] Ball, p. 100[20] Horvitz, Leslie (2002). Eureka!: Scientific Breakthroughs That Changed The World. New York: John Wiley. p. 43. ISBN 9780471233411.

OCLC 50766822.[21] Ball, p. 101[22] Newlands, John A. R. (1864-08-20). "On Relations Among the Equivalents" (http:/ / web. lemoyne. edu/ ~giunta/ EA/ NEWLANDSann.

HTML#newlands3). Chemical News 10: 94–95. .[23] Newlands, John A. R. (1865-08-18). "On the Law of Octaves" (http:/ / web. lemoyne. edu/ ~giunta/ EA/ NEWLANDSann.

HTML#newlands4). Chemical News 12: 83. .[24] Bryson, Bill (2004). A Short History of Nearly Everything. London: Black Swan. pp. 141–142. ISBN 9780552151740.[25] Ball, pp. 100–102[26] Pullman, Bernard (1998). The Atom in the History of Human Thought. Translated by Axel Reisinger. Oxford University Press. p. 227.

ISBN 0-19-515040-6.[27] Ball, p. 105[28] Atkins, P. W. (1995). The Periodic Kingdom. HarperCollins Publishers, Inc.. p. 87. ISBN 0-465-07265-8.[29] Ball, p. 111[30] Adloff, Jean-Pierre; Kaufman, George B. (2005-09-25). Francium (Atomic Number 87), the Last Discovered Natural Element (http:/ /

chemeducator. org/ sbibs/ s0010005/ spapers/ 1050387gk. htm). The Chemical Educator 10 (5). Retrieved on 2007-03-26.[31] Hoffman, D. C.; Lawrence, F. O.; Mewherter, J. L.; Rourke, F. M. (1971). "Detection of Plutonium-244 in Nature" (http:/ / www. nature.

com/ nature/ journal/ v234/ n5325/ abs/ 234132a0. html). Nature 234 (5325): 132–134. Bibcode 1971Natur.234..132H.doi:10.1038/234132a0. .

[32] Ball, p. 123[33] "[IUPAC]Element 112 is Named Copernicium" (http:/ / www. iupac. org/ web/ nt/ 2010-02-20_112_Copernicium). iupac.org.

doi:10.1351/PAC-REP-08-03-05. . Retrieved 2010-06-12.[34] Barber, Robert C.; Karol, Paul J; Nakahara, Hiromichi; Vardaci, Emanuele; Vogt, Erich W. (2011). "Discovery of the elements with atomic

numbers greater than or equal to 113 (IUPAC Technical Report)". Pure Appl. Chem.. doi:10.1351/PAC-REP-10-05-01.

Bibliography• Ball, Philip (2002). The Ingredients: A Guided Tour of the Elements. Oxford University Press.

ISBN 0-19-284100-9.• Moore, John (2003). Chemistry For Dummies. New York: Wiley Publications. p. 111. ISBN 978-0-7645-5430-8.

OCLC 51168057.

Further reading• Bouma, J. (1989). "An Application-Oriented Periodic Table of the Elements". J. Chem. Ed. 66: 741.

Bibcode 1989JChEd..66..741B. doi:10.1021/ed066p741.• Hjørland, Birger (2011). "The periodic table and the philosophy of classification" (http:/ / ucla. academia. edu/

EricScerri/ Papers/ 432740/ Forum_The_Philosophy_of_Classification). Knowledge Organization 38 (1): 9–21.Retrieved 2011-03-13.

• Mazurs, E.G (1974). Graphical Representations of the Periodic System During One Hundred Years. Alabama:University of Alabama Press.

• Scerri, Eric (2007). The periodic table: its story and its significance. Oxford: Oxford University Press.ISBN 0-19-530573-6.

Periodic table 11

External links• Interactive periodic table (http:/ / www. ptable. com/ )• Video periodic table (http:/ / www. periodicvideos. com)• WebElements (http:/ / www. webelements. com/ )• IUPAC periodic table (http:/ / www. iupac. org/ reports/ periodic_table/ index. html)• 118 elements (http:/ / www. periodicvideos. com): The Periodic Table of Videos made by Brady Haran, featuring

Martyn Poliakoff and others, at the University of Nottingham.• A catalog of various forms of the periodic table (http:/ / www. meta-synthesis. com/ webbook/ 35_pt/

pt_database. php)

Article Sources and Contributors 12

Article Sources and ContributorsPeriodic table  Source: http://en.wikipedia.org/w/index.php?oldid=445881579  Contributors: 129.186.19.xxx, 158.252.248.xxx, 1993 lol, 203.109.250.xxx, 28bytes, 64.26.98.xxx, A-giau, A. diM., Aa35te, Aaron Schulz, Abc518, Aciddoll, Aco47, Adam Bishop, Adamsbriand, Adashiel, AdiJapan, AdjustShift, Adult Swim Addict, Af648, Ageekgal, Ahoerstemeier, AlHalawi, Alansohn,AlimanRuna, Alkivar, Allstarecho, Alphachimp, Altenmann, Alvinrune, Ambuj.Saxena, Anastrophe, Andre Engels, Andrew11, Andrewrost3241981, Android 93, Andy120290, Angrysockhop,Angusmclellan, AnjuX, Anna Lincoln, Anoop.m, Antandrus, Aonrotar, Apastrophe, Arbitrarily0, Archenzo, Archimerged, Arjun Rana, Arkrishna, Arman Cagle, Asyndeton, Aushulz,Avicennasis, Avsa, AxG, AxelBoldt, Az1568, AzaToth, BRG, BTolli, BalkanFever, Barneca, Bcorr, Beanyk, Beetstra, Benbest, Bensaccount, Betaeleven, Bevo, Bigsnake 19, Bigtimepeace, BillSayre, BirgerH, Bkell, Bkonrad, Black and White, Blanchardb, Blargblarg89, Blobglob, BlueEarth, Bluemoose, Bob, Bob Jonkman, Bobblewik, Bobby131313, Bobet, Bobo192, Bonaparte,Borgdylan, Borislav, Bovineone, Brendan Moody, BrianKnez, BrianScanlan, Brianga, Briséis, Brockert, BrotherFlounder, Bryan Derksen, Btg2290, C0RNF1AK35, CBM, CWenger, Cacycle,Caesura, Caknuck, Caltas, Calvero JP, Can't sleep, clown will eat me, Canderson7, Canjth, CapitalR, Car132, Carbon-16, Caster23, Cataclysm, CharlesC, Chengyq19942007, ChickenMarengo,Chill doubt, Cholmes75, Chris 73, Chris the speller, ChrisSmol, Chrisk12, Christian List, Christophenstein, Cimex, Ckatz, Clawson, Clemwang, ClockworkSoul, Clorox, Closedmouth,Cobaltcigs, Coffee, Computerjoe, Conget, ConnTorrodon, Conny, Corpx, Corsair18, Corvus cornix, Courcelles, Cpl Syx, Creator58, Cryptic C62, Cst17, Ctachme, Curb Chain, Cwolfsheep,Cyan, D6, DARTH SIDIOUS 2, DBragagnolo, DGaw, DMacks, DNAmaster, DR04, DRosenbach, DSachan, DVD R W, Dagrimdialer619, Dale101usa, Dalta, Damnreds, Dan Koehl, DanKeshet,DancingPenguin, Danski14, Darklama, Darrien, Darth Panda, Darthchaos, Davewild, David Edgar, David Gerard, David Little, DavidOaks, Dawn Bard, Dbchip, Dcljr, Ddon, Debresser,Deeptrivia, Deeryh01, Degg444, Dekisugi, Dellacomp, Delldot, DeltaQuad, Den fjättrade ankan, Denelson83, Deon, DerHexer, Derek.cashman, Deus Ex, Dffgd, Dhollm, Digger3000,Dillard421, Dinamik, Discospinster, DixonD, Dlorang, Dmmaus, Dmoss, Dmsc893, DocWatson42, Dogposter, Dougofborg, Dpbsmith, Dpeters11, Drbogdan, Dreadstar, Dreamyshade, Drmies,Drova, Drunkenmonkey, Dtgm, Dustimagic, Dwaipayanc, Dyknowsore, EH74DK, EL Willy, EagleOne, EamonnPKeane, EarthmatriX, EconoPhysicist, Edcolins, Eddideigel, Edgar181, Egil,Eirik (usurped), El C, Elcobbola, Eli84, Eliashedberg, Elk Salmon, Elkman, Elly4web, Elsweyn, Emperorbma, EnDaLeCoMpLeX, EncMstr, EngineerScotty, Enviroboy, Ephebi, Eric119, ErikZachte, Escape Orbit, Essam Sharaf, Eszett, EugeneZelenko, Eupedia, Everybody's Got One, Everyking, Excirial, Exert, Exigentsky, Exodecai101, Extransit, FF2010, Fabartus, Feline1, FelixWan, Femto, Fifo, Figma, Finngall, Fishekad, FisherQueen, FlyingToaster, Fonzy, Fork me, Fredrik, FreplySpang, Freywa, Full On, Fuzzform, Fyandcena, GDonato, GHe, GabrielF, Gadfium,Garudabd, Gawaxay, Gemmi3, Gentgeen, GeorgeTopouria, Georgedriver, Gffootball58, Ghirlandajo, Giftlite, Gilliam, Giraffedata, Glenn L, Gobonobo, Gona.eu, Gonzonoir, Gopal81,Gprince007, Grahamec, Graniggo, Greyhood, Grick, Grim23, Gromlakh, Gurch, Gurchzilla, Gwernol, HGB, HLewis, Haeleth, Hairy Dude, Hak-kâ-ngìn, HalfShadow, Hamilton hogs,Hamtechperson, Hardwigg, Hdt83, Headbomb, Heidslovesearl, Helixblue, Helixer, Heron, Hh73wiki, HiDrNick, Hiddenfromview, Honeycake, Hughbert512369, Hut 8.5, Hv, Hwn tls,Hyuuganeji0123, I dream of horses, I2yu, Ian Fraser at Temple Newsam House, IanManka, Icairns, Ilovestars89, Imawsome 09, Imnotminkus, Infrogmation, Inkypaws, Insanity Incarnate, IntoThe Fray, InverseHypercube, Iosef, Iskander32, Islander, Itub, Iwilcox, Ixfd64, J.delanoy, J0lt C0la, JDT1991, JForget, JNW, JRSP, Jachapo, Jack Merridew, Jack the Stripper, Jack who built thehouse, Jackfork, Jaeger Lotno, Jake Fuersturm, Jared Preston, Jauerback, Jaxl, Jaybo007, Jazjaz92, Jean-claude perez, Jeff G., Jeffq, JenR32, Jengod, Jhd, Jiang, Jimmy Slade, JinJian,Jinglesmells999, Jklin, Jmocenigo, Jni, Jobroluver98, JodyB, Joe Decker, Joeclark, John254, JohnBlackburne, JohnWittle, Johnlogic, Johnnieblue, Jojit fb, Joka1991, Jonmwang, Jose77,Joshlepaknpsa, Jossi, Jpatokal, Juanpdp, Junglecat, Jusjih, Just James, Just another user 2, Juve82, Jwissick, Kaeso Dio, Kaiba, Kaischwartz, Kangxi emperor6868, Kanonkas, Kateshortforbob,Kathryn NicDhàna, Kbdank71, Keegan, Keenan Pepper, Kelvin35, Kerotan, Kesac, Ketsuekigata, Khalid Mahmood, Kingpin13, Kinston eagle, Kiran the great, Kitrkatr, Kiwi137, Klenje,Knowhow, KnowledgeOfSelf, Koavf, Konczewski, Kosebamse, KotVa, Kragenz, Kungfuadam, Kwamikagami, Kwekubo, Kwertii, La Pianista, Lani123, Lanthanum-138, LarryMorseDCOhio,LeaveSleaves, Lee Daniel Crocker, LegitimateAndEvenCompelling, Lightmouse, Lincmad, Littlealien182, LiveAgain, LizardJr8, Logical2u, Lollerskates, Lowellian, LtPowers, Lucent, LuckasBlade, Lucky 6.9, Luhar1997, LuigiManiac, Lumos3, Luna Santin, Lupin, Luuva, MC10, MER-C, Mac Davis, MacTire02, Madhero88, MairAW, ManiF, MarcoTolo, Marek69, Martin451,Mass09, Materialscientist, Mathmarker, Matticus78, Mattvirajrenaudbrandon, Maurakt, Mav, Maximus Rex, Maxus96, McSly, Mchavez, Mdebets, Melchoir, Memorymike, Mentifisto,Metacomet, Methyl, Mets501, Michael Hardy, Michael phan, Michael93555, Michaelbusch, Michfg, Mike Rosoft, Mikemoral, Milesnfowler, Miranda, Misza13, Mkouklis, Mo0, Moneya,Monkeybutt5423, Moop stick, Mpatel, MrFish, Munkimunki, Musicloudball, Mxn, Myanw, Mycroft.Holmes, Nagasturg, NarSakSasLee, Nat682, Natasha.fielding, Ndufour, Nebular110,Negovori, NeilN, Nemti, NeoJustin, Nergaal, Netalarm, NewEnglandYankee, Nezzington, NicholasSThompson, Nick, Nishkid64, Nivix, Nk, No Guru, Noctibus, Nofutureuk, Noisy,NolanRichard, Nolimits5017, Nopetro, Notapotato, Nposs, Nsim, Nsimya, NullAshton, Nuttycoconut, Nv8200p, Nyenyec, Oblivious, Ohnoitsjamie, Okome, Olin, Olivier, Omgosh2, Onorem,Opabinia regalis, OrangeDog, Orzetto, Oxymoron83, PDH, Pappapasd, Pathoschild, Patrick, Paulbkirk, Pearrari, Pearson3372, Peter Ellis, Petergans, Peterwhy, Petri Krohn, Pezzells, Phaedrus86,Phantomsteve, Pharaoh of the Wizards, Philip Trueman, Philippe, Philthecow, Phisite, Physchim62, Pi Guy 31415, PiMaster3, Piano non troppo, Pickweed, PierreAbbat, Pinethicket, Piolinfax,Pirateer, Pitcroft, Plumbago, Plutonium55, Poccil, PoliteCarbide, Polyamorph, Poor Yorick, PostScript, Precious Roy, PrestonH, Pshent, Psinu, Psycho Kirby, Ptdecker, Pumeleon, Pwntskater,Quilbert, Qwertyus, Qxz, R8R Gtrs, RDBrown, RG2, RJFJR, RJHall, RUL3R, Racantrell, Radagast, RadiantRay, Ragesoss, Rainwarrior, Ran, Random user 8384993, Rarb, Rasmus vendelboe,Rawling, Realm up, Redaktor, Reddi, Reedy, Rescorbic, Rettetast, RexNL, Reywas92, Rfc1394, Rich Farmbrough, Richard777, RichardF, Rifleman 82, Rihanij, Rintrah, Rjstott, RobertSkyhawk, RobertG, Roentgenium111, Romanm, Ronz, Roscelese, Rowlaj01, RoyBoy, Rsrikanth05, Rudjek, Ryan Postlethwaite, RyanCross, Ryanminier, Ryoutou, Ryuken14, SJP, SWAdair,Sadi Carnot, Salsa Shark, Sam Hocevar, Samboy, Sanchom, Sango123, Sankalpdravid, Saperaud, Sat84, Satori Son, Savidan, Scarian, Scerri, Sch00l3r, Schneelocke, Schoen, Schzmo,Scientizzle, Sean Whitton, SeanMack, Secretlondon, Segalsegal, Selket, Semper discens, Sergeibernstein, SeventyThree, Shalmanese, Shanes, Shawnhath, ShayneRyan, Shellreef, Shizhao,Shoessss, Shpakovich, Shrikethestalker, Sifaka, Sillyboy67, Sionus, Skatebiker, Sl, Slash, Smack, Smartweb, Smurrayinchester, Snoyes, SoSaysChappy, Someone else, SparrowsWing,SpeedyGonsales, Spesh531, SpookyMulder, SpuriousQ, Squadoosh, SquirrelMonkeySpiderFace, Srnec, Stan Shebs, Stassats, StaticVision, Stefan, Stephan Leeds, Stephenb, Stone, Stormie,Strongbadmanofme, StuFifeScotland, Suidafrikaan, Suisui, Sunborn, Sunshine4921, Superjustinbros., Supertigerman, Superworms, Supia, Suuperturtle, Sweetness46, Syhon, TJRC, TMC,Tabfugnic, Tarantola, Taras, Tarquin, Taylor4452, Techdawg667, Template namespace initialisation script, Tempnegro, Tempodivalse, Tempshill, Terfili, TerraFrost, TestPilot, Tetracube,Texture, Tf1321, Tfts, The Anome, The High Fin Sperm Whale, The Thing That Should Not Be, The undertow, The way, the truth, and the light, TheOtherJesse, TheRanger, TheSickBehemoth,TheVault, Thecroman, Thedjatclubrock, Thehelpfulone, Theresa knott, Thom.fynn, Thomasrive, Thompsontm, Thunderboltz, Tiddly Tom, Tide rolls, TigerShark, Til Eulenspiegel, Timex987,Timir2, Timo Honkasalo, Tiptoety, Tjlafave, Tom dl, Tom harrison, Tomertomer, Tomi, Tomilee0001, Tommy2010, TotalSpaceshipGuy3, TranClan, Traroth, Turn off 2, Twonernator, Túrelio,U10ajf, UU, Ulric1313, Unyoyega, User A1, V8rik, Van helsing, Vanished user 39948282, Vbs, Versus22, Vidshow, VinceB, Viper275, Viskonsas, Visor, Vitall, Vlad4599, Vsmith, Vssun,WFPM, WOWGeek, Waldir, Walton One, Wapcaplet, WarthogDemon, Wasitgood, Wasitgood69, Wavelength, Wd930, WebElements, Weetoddid, Weyes, Whosyourjudas, Why Not A Duck,Wifiless, WikHead, Wiki alf, Wikiak, Wikiman7, Wimt, WingedSkiCap, Wknight94, WormRunner, Wtmitchell, XJamRastafire, Xhaoz, Xoyorkie13, Yahya Abdal-Aziz, Yamamoto Ichiro,Yankeesrule3, Ydoommas, Yekrats, Ylime715, Yoenit, Yosri, Youandme, Yvonr, Zach112233, Zainiadragon10000, Zaphod Beeblebrox, Zarxos, Zed0, Zerotjon, Zhieaanm, Ziaix, ZooFari, ÆvarArnfjörð Bjarmason, ܥܝܪܐܩ, පසිඳු කාවින්ද, 2151 anonymous edits

Image Sources, Licenses and ContributorsFile:Ionization energies.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Ionization_energies.svg  License: Public Domain  Contributors: RJHallFile:Periodic Table structure.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Periodic_Table_structure.svg  License: Creative Commons Attribution-Share Alike  Contributors:Sch0013rFile:Periodic table.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Periodic_table.svg  License: Public Domain  Contributors: User:CepheusFile:Periodic table monument.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Periodic_table_monument.jpg  License: Creative Commons Attribution-Sharealike 2.0  Contributors:http://www.flickr.com/people/mmmdirt/Image:Mendeleev's 1869 periodic table.png  Source: http://en.wikipedia.org/w/index.php?title=File:Mendeleev's_1869_periodic_table.png  License: Public Domain  Contributors: Originaluploader was Sadi Carnot at en.wikipediaFile:Medeleeff by repin.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Medeleeff_by_repin.jpg  License: Public Domain  Contributors: Hailey C. Shannon, J.M.Domingo, Kevyn,Kneiphof, Maximaximax, OldakQuill, Proktolog, Ragesoss, Shakko, Solon, XJamRastafire, 竹麦魚(Searobin), 2 anonymous edits

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