Chemical elements

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Chemical elements — "the substances from which everything tangible is made"[1] — are those particular types of matter of which a macroscopic sample[2] of each element type is constituted of a population solely of a single type (or species) of atom — each element type unique in virtue of the number of protons in each of its sample population's constituent atoms' nuclei, referred to as the atomic number of the element type. On Earth 94 different types of atoms occur in nature, and therefore nature supplies 94 different element types, each element type having its unique atomic number, and each characterized by a unique set of physical and chemical properties.[3]

People from all walks of life know something about many different elements from everyday life, even if they do not recognize them as elements. They include: Hydrogen (H1), used to make hydrogen bombs. Helium (He2), used to make party balloons float. Lithium (Li3), used to make batteries for cellphones. Oxygen (O8), in the air we breathe. Neon (Ne10), in 'neon' lights. Sodium (Na23, nutritionists advise consuming sparingly in foods and from salt shaker.

All matter directly perceptible by the human senses — whether solid, liquid or gas — is composed of one or more elements. Typically, elements are found in nature in the form of populations of atoms, often with the atoms of other elements, as compounds (e.g., iron ore, a population of unit compounds each of iron and oxygen atoms) or as mixtures. Some elements are abundant on Earth. For example, the elements hydrogen and oxygen, as the compound water, H2O, make up the bulk of Earth's oceans, seas, lakes, rivers, and ponds, and make up the bulk (mass) of living cells and multicellular oganisms.[4] For another example, the element carbon supplies the backbone of numerous species of essential compounds of all animal and plant life on Earth as well of all the fossil fuels (natural gas, petroleum and coal), which are the remains of plant material that once lived. Some compounds may consist of one element only, for instance a nugget of pure gold is made up solely of gold atoms arranged in crystalline form. Very often gold is not pure but an alloy — a mixture — of the elements copper, silver, and gold. Oxygen gas consists of entities [see molecule] each having two oxygen atoms chemically bonded to each other, hence the gas consists of the element oxygen only.

Two substances consisting of the same single element may have very different chemical and physical properties, e.g., graphite, used as lubricant, and diamond, used to harden drill tips, both pure carbon. This phenomenon is known as allotropy. Oxygen atoms (O), oxygen gas (O2), and ozone (O3) — all found in the atmosphere — are allotropes of the same element, as they have different chemical and physical properties, yet each consists solely of [oxygen] atoms whose nuclei have identical numbers of protons,

Some of the 94 elements , such as the gas neon, are very rare on Earth. Some elements are stable, and will live as long as the universe, while some, known as the radioactive elements, have finite life times and decay into other elements while emitting radiation. For example, plutonium is a well-known radioactive element.

In addition to the 94 elements that occur naturally on Earth, about 23 other known elements that do not occur naturally on Earth have been man-made and are characterized by their constituent atoms having very short life times and being radioactive.

As noted, the atoms of each of the elements are distinguished by a unique atomic number, an integral (whole) number, symbolized Z, indicating the number of protons in the atom's nucleus. As protons each carry a positive charge, Z gives the positive charge of the nucleus in units of the so-called elementary charge, symbolized e. It is known that Z electrons (of charge −e, or negative e, and of much smaller mass than the proton) "orbit" the nucleus of an atom, so that an atom as a whole is electrically neutral. The following elements have their values of Z (Z-values) in brackets: hydrogen(1), oxygen(8), carbon(6), neon(10), plutonium(94). The naturally occurring elements have Z-values from 1 to 94 (with plutonium being extremely rare in nature and mainly man-made). The exclusively man-made elements on Earth run from Z = 95 to 118. The names of the elements are of historical origin and may differ among languages for an element. The atomic number (Z), on the other hand, is a unique and universal label of an element, as is its international chemical symbol consisting of one or two letters.

Whereas an element consists of a single species of atom characterized by a unique atomic number, many such species occur in varieties, called isotopes. The isotopes of an element differ among themselves by the number of neutrons in the nucleus, not in the number of protons. As neutrons have mass, and mass similar to that of protons, the isotopes of a given element have differing masses. For example, the most abundant form of hydrogen has a nucleus consisting only of a proton, the fairly rare isotope deuterium has a nucleus that contains one proton and one neutron, and the rarer isotope, tritium, has a nucleus that contains one proton and two neutrons. All three isotopes, while having differing masses, have by definition the same atomic number (=1) and hence are variations, or isotopes, of the same element.

There is a maximum to the number of unique elements that can exist due to the fact that a nucleus contains Z positively charged particles (protons). Those repel each other by Coulomb forces but can remain together by a special nuclear force referred to as the strong nuclear force. At a certain large number of protons the strong nuclear force will begin to lose out to the Coulomb force — increasingly so with increasing numbers of protons — and the nucleus will no longer be stable. This is likely to happen between Z = 120 and Z = 130.

For a long time, it was thought that elements were unchangeable, that one element could not be converted into another. Alchemists searched for many centuries in vain for the transmutation of the element lead into gold. However, when in 1919 Ernest Rutherford and coworkers showed the transmutation of the element nitrogen into the element oxygen, it became clear that elements can be transmuted.

The modern concept of element differs greatly from the Aristotelian concept. Aristotle recognized four elements: fire, water, earth and air, and postulated that they can be converted into each other. He wrote:

"….the elements are the primary constituents of bodies....
An element, we take it, is a body into which other bodies may be analysed, present in them potentially or in actuality
(which of these, is still disputable), and not itself divisible into bodies different in form. That, or something like it,
is what all men in every case mean by element….every body is either an element or composed of elements…."

    —Aristotle. On the Heavens Book III. Translated by J.L. Stocks.


Tables

See Atomic electron configuration for the orbital occupancies of atoms in their so-called ground state.
See also Periodic Table of Elements.

Chemical elements sorted on chemical symbol (CS)


CSNameZ CSNameZ CSNameZ

AcActinium 89 GdGadolinium 64 Po Polonium 84
AgSilver 47 GeGermanium 32 Pr Praseodymium 59
AlAluminum 13 H Hydrogen 1 Pt Platinum 78
AmAmericium 95 HeHelium 2 Pu Plutonium 94
ArArgon 18 HfHafnium 72 Ra Radium 88
AsArsenic 33 HgMercury 80 Rb Rubidium 37
AtAstatine 85 HoHolmium 67 Re Rhenium 75
AuGold 79 HsHassium 108 Rf Rutherfordium 104
B Boron 5 I Iodine 53 Rg Roentgenium 111
BaBarium 56 InIndium 49 Rh Rhodium 45
BeBeryllium 4 IrIridium 77 Rn Radon 86
BhBohrium 107 K Potassium 19 Ru Ruthenium 44
BiBismuth 83 KrKrypton 36 S Sulfur 16
BkBerkelium 97 LaLanthanum 57 Sb Antimony 51
BrBromine 35 LiLithium 3 Sc Scandium 21
C Carbon 6 LrLawrencium 103 Se Selenium 34
CaCalcium 20 LuLutetium 71 Sg Seaborgium 106
CdCadmium 48 MdMendelevium 101 Si Silicon 14
CeCerium 58 MgMagnesium 12 Sm Samarium 62
CfCalifornium 98 MnManganese 25 Sn Tin 50
ClChlorine 17 MoMolybdenum 42 Sr Strontium 38
CmCurium 96 MtMeitnerium 109 Ta Tantalum 73
CoCobalt 27 N Nitrogen 7 Tb Terbium 65
CrChromium 24 NaSodium 11 Tc Technetium 43
CsCesium 55 NbNiobium 41 Te Tellurium 52
CuCopper 29 NdNeodymium 60 Th Thorium 90
DbDubnium 105 NeNeon 10 Ti Titanium 22
DsDarmstadtium 110 NiNickel 28 Tl Thallium 81
DyDysprosium 66 NoNobelium 102 Tm Thulium 69
ErErbium 68 NpNeptunium 93 U Uranium 92
EsEinsteinium 99 O Oxygen 8 V Vanadium 23
EuEuropium 63 OsOsmium 76 W Tungsten 74
F Fluorine 9 P Phosphorus 15 Xe Xenon 54
FeIron 26 PaProtactinium 91 Y Yttrium 39
FmFermium 100 PbLead 82 Yb Ytterbium 70
FrFrancium 87 PdPalladium 46 Zn Zinc 30
GaGallium 31 PmPromethium 61 Zr Zirconium 40


Chemical elements sorted on atomic number (Z)


ZNameCS ZNameCS ZNameCS

1 Hydrogen H 38 Strontium Sr 75 Rhenium Re
2 Helium He 39 Yttrium Y 76 Osmium Os
3 Lithium Li 40 Zirconium Zr 77 Iridium Ir
4 Beryllium Be 41 Niobium Nb 78 Platinum Pt
5 Boron B 42 Molybdenum Mo 79 Gold Au
6 Carbon C 43 Technetium Tc 80 Mercury Hg
7 Nitrogen N 44 Ruthenium Ru 81 Thallium Tl
8 Oxygen O 45 Rhodium Rh 82 Lead Pb
9 Fluorine F 46 Palladium Pd 83 Bismuth Bi
10 Neon Ne 47 Silver Ag 84 Polonium Po
11 Sodium Na 48 Cadmium Cd 85 Astatine At
12 Magnesium Mg 49 Indium In 86 Radon Rn
13 Aluminum Al 50 Tin Sn 87 Francium Fr
14 Silicon Si 51 Antimony Sb 88 Radium Ra
15 Phosphorus P 52 Tellurium Te 89 Actinium Ac
16 Sulfur S 53 Iodine I 90 Thorium Th
17 Chlorine Cl 54 Xenon Xe 91 Protactinium Pa
18 Argon Ar 55 Cesium Cs 92 Uranium U
19 Potassium K 56 Barium Ba 93 Neptunium Np
20 Calcium Ca 57 Lanthanum La 94 Plutonium Pu
21 Scandium Sc 58 Cerium Ce 95 Americium Am
22 Titanium Ti 59 Praseodymium Pr 96 Curium Cm
23 Vanadium V 60 Neodymium Nd 97 Berkelium Bk
24 Chromium Cr 61 Promethium Pm 98 Californium Cf
25 Manganese Mn 62 Samarium Sm 99 Einsteinium Es
26 Iron Fe 63 Europium Eu 100 Fermium Fm
27 Cobalt Co 64 Gadolinium Gd 101 Mendelevium Md
28 Nickel Ni 65 Terbium Tb 102 Nobelium No
29 Copper Cu 66 Dysprosium Dy 103 Lawrencium Lr
30 Zinc Zn 67 Holmium Ho 104 Rutherfordium Rf
31 Gallium Ga 68 Erbium Er 105 Dubnium Db
32 Germanium Ge 69 Thulium Tm 106 Seaborgium Sg
33 Arsenic As 70 Ytterbium Yb 107 Bohrium Bh
34 Selenium Se 71 Lutetium Lu 108 Hassium Hs
35 Bromine Br 72 Hafnium Hf 109 Meitnerium Mt
36 Krypton Kr 73 Tantalum Ta 110 Darmstadtium Ds
37 Rubidium Rb 74 Tungsten W 111 Roentgenium Rg

Explanation of names

  1. Ag (silver) is from Argentum
  2. Au (gold) is from Aurum
  3. Cu (copper) is from Cuprum
  4. Fe (iron) is from Ferrum
  5. Hg (mercury) is from Hydrargyrum
  6. K (potassium) is from Kalium
  7. Na (sodium) is from Natrium
  8. Pb (lead) is from Plumbum
  9. Sb (antimony) is from Stibium
  10. Si (silicon) is from Silicium
  11. Sn (tin) is from Stannum
  12. W (tungsten) is from Wolfram
  13. Man-made elements Z = 112, ..., 118 are not listed

References and notes

  1. Atkins PW. (1995, 1997) The Periodic Kingdom: A Journey into the Land of the Chemical Elements. (Full-Text). New York: Basic Books. ISBN 9780465072668.
    • Publisher´s Description:  Come on a journey into the heart of matter—and enjoy the process!—as a brilliant scientist and entertaining tour guide takes you on a fascinating voyage through the Periodic Kingdom, the world of the elements. The periodic table, your map for this trip, is the most important concept in chemistry. It hangs in classrooms and labs throughout the world, providing support for students, suggesting new avenues of research for professionals, succinctly organizing the whole of chemistry. The one hundred or so elements listed in the table make up everything in the universe, from microscopic organisms to distant planets. Just how does the periodic table help us make sense of the world around us? Using vivid imagery, ingenious analogies, and liberal doses of humor P. W. Atkins answers this question. He shows us that the Periodic Kingdom is a systematic place. Detailing the geography, history and governing institutions of this imaginary landscape, he demonstrates how physical similarities can point to deeper affinities, and how the location of an element can be used to predict its properties. Here’s an opportunity to discover a rich kingdom of the imagination kingdom of which our own world is a manifestation.
  2. Note: A sample large enough to be observed without a microscope.
  3. According to James B. Calvert: The trite phrase "the 92 naturally-occurring chemical elements" is often seen, but is incorrect. There are only 88 naturally-occuring chemical elements. The elements 43 [technetium], 61 [promethium], 85 [astatine] and 87 [francium] have no stable isotopes, and none of long half-life, so they are not naturally present. Small amounts are made in nuclear reactions induced by cosmic rays and nuclear tests, but these soon disappear. If you protest that these should be included, then so should Np [neptunium] and Pu [plutonium], which are produced by the absorption of neutrons arising from spontaneous fission of uranium and thorium, and then there would be 94 naturally-occurring elements. If you wait long enough, there will only be 81 naturally-occurring elements, since everything beyond lead has only unstable isotopes, though some are of very long half-life, and have survived since the beginning, fathering their radioactive series. Any way you look at it, there are not just 92 naturally-occurring chemical elements. See: http://mysite.du.edu/~jcalvert/phys/92.htm
  4. Note: A typical living cell consists of 75-85% water by mass.