Chemical element
5659
226136895
2008-07-16T23:57:42Z
Robbot
25261
robot Adding: [[fy:Elemint]]
[[Image:Periodic table.svg|450px|thumb|right|The [[periodic table]] of the chemical elements]]
A '''chemical element''' is a type of atom that is distinguished by its [[atomic number]]; that is, by the number of [[proton]]s in its [[atomic nucleus|nucleus]]. The term is also used to refer to a pure chemical [[Chemical substance|substance]] composed of atoms with the same number of protons.<ref>[[Compendium of Chemical Terminology]], [http://goldbook.iupac.org/C01022.html chemical element]</ref>
Common examples of elements are [[hydrogen]], [[carbon]], [[nitrogen]], and [[oxygen]]. In total, 117 elements have been observed as of 2007, of which 94 occur naturally on Earth. Elements with atomic numbers 83 or higher ([[bismuth]] and above) are inherently unstable, and undergo [[radioactive decay]]. Of the first 82 elements, 80 have stable [[isotope]]s. Elements 43 and 61 ([[technetium]] and [[promethium]]) have no stable isotopes, and decay. The elements from 83 to atomic number 94 that have no stable nuclei, are nevertheless found in nature, either surviving as remnants of the primordial stellar nucleosynthesis which produced the elements in the solar system, or else as produced newly as short-lived daughter-isotopes in the natural decay of [[uranium]] and [[thorium]].<ref>A. Earnshaw, Norman Greenwood. ''Chemistry of the Elements, Second Edition''. Butterworth-Heinemann, 1997</ref>
All [[chemical matter]] consists of these elements. New elements of higher atomic number are discovered from time to time, as products of artificial [[nuclear reaction]]s.
==History==
[[Image:Mendeleev's 1869 periodic table.png|300px|thumb|[[Mendeleev]]'s 1869 [[periodic table]]]]
Several ancient [[Philosophy|philosophies]] used a set of archetypal [[classical element]]s to explain patterns in [[nature]]. The term 'element' was originally used to refer to a [[state of matter]] (solid/earth, liquid/water, gas/air, and plasma/fire) or a [[phase of matter]] (as in the [[Chinese philosophy|Chinese]] ''[[Wu Xing]]''), rather than the chemical elements of modern science. The [[Greek philosophy|Greek]], [[Indian philosophy|Indian]] (''[[Tattva]]'' and ''[[Mahābhūta]]'') and [[Japanese philosophy|Japanese]] (''[[Five elements (Japanese philosophy)|go dai]]'') traditions essentially had the same five elements: [[Air (classical element)|Air]], [[Earth (classical element)|Earth]], [[Fire (classical element)|Fire]], [[Water (classical element)|Water]] and [[Aether (classical element)|Aether]].
The term 'elements' (''stoicheia'') was first used by the Greek philosopher [[Plato]] in about 360 BCE, in his dialogue [[Timaeus (dialogue)|Timaeus]], which includes a discussion of the composition of inorganic and organic bodies and is a rudimentary treatise on chemistry. Plato assumed that the minute particle of each element corresponded to one of the [[regular polyhedron|regular polyhedra]]: [[tetrahedron]] (fire), [[octahedron]] (air), [[icosahedron]] (water), and [[cube]] (earth).<ref>{{Fact|date=December 2007}}<!-- Nowhere in the cited article are the regular polyhedra mentioned, individually or collectively -->{{cite web | last = Hillar | first = Marian | year = 2004 | url = http://www.socinian.org/aristotles_de_anima.html | title = The Problem of the Soul in Aristotle's De anima | publisher = NASA WMAP | accessdate = 2006-08-10 }}</ref>
Adding to the four elements of the Greek philosopher [[Empedocles]], in about 350 BC, [[Aristotle]] also used the term "element" and conceived of a fifth element called "[[Aether (classical element)|quintessence]]", which formed the heavens. Aristotle defined an element as:
{{quote|'''Element''' – one of those bodies into which other bodies can be decomposed and which itself is not capable of being divided into other.<ref> {{cite book | last=Partington | first=J.R. | year=1937 | title=A Short History of Chemistry | location=New York | publisher=Dover Publications, Inc. | isbn=0486659771}}</ref>}}
Building on the theory in ''circa'' 790, [[Alchemy and chemistry in Islam|Arabian chemist and alchemist]], [[Geber|Jabir ibn Hayyan]] (Geber), postulated that [[metal]]s were formed out of two elements: [[Sulfur|sulphur]], ‘the stone which burns’, which characterized the principle of combustibility, and [[Mercury (element)|mercury]], which contained the idealized principle of metallic properties.<ref name="r8">Strathern, Paul. (2000). Mendeleyev’s Dream – the Quest for the Elements. New York: Berkley Books.</ref> Shortly thereafter, this evolved into the Arabic concept of the three principles: sulphur giving flammability or combustion, mercury giving volatility and stability, and [[Salt (chemistry)|salt]] giving solidity.
In the 10th century, [[Islamic medicine|Persian physician]] and alchemist [[Muhammad ibn Zakarīya Rāzi]] (Rhazes) wrote the ''Doubts concerning Galen'', in which he refuted both the [[Galen]]ic medical theory of [[Humorism|four humours]] and the underlying ancient concept of four classical elements. He carried out an [[experiment]] which would upset these theories by inserting a liquid with a different temperature into a body resulting in an increase or decrease of bodily heat, which resembled the temperature of that particular fluid. Razi noted particularly that a warm drink would heat up the body to a degree much higher than its own natural temperature, thus the drink would trigger a response from the body, rather than transferring only its own warmth or coldness to it. Razi's chemical experiments suggested other qualities of matter, such as "[[oil]]iness" and "[[sulfur]]ousness", or [[inflammability]] and [[salinity]], which were not readily explained by the traditional fire, water, earth and air division of elements.<ref>G. Stolyarov II (2002), "Rhazes: The Thinking Western Physician", ''The Rational Argumentator'', Issue VI</ref>
In 1524, Swiss chemist [[Paracelsus]] adopted Aristotle’s four element theory, but reasoned that they appeared in bodies as Geber’s three principles. Paracelsus saw these principles as fundamental, and justified them by recourse to the description of how wood burns in fire. Mercury included the cohesive principle, so that when it left in smoke the wood fell apart. Smoke represented the volatility (the mercury principle), the heat-giving flames represented flammability (sulphur), and the remnant ash represented solidity (salt).<ref name="r8"/>
In 1669, German physician and chemist [[Johann Becher]] published his Physica Subterranea. In modification on the ideas of Paracelsus, he argued that the constituents of bodies are air, water, and three types of earth: ''terra fluida'', the mercurial element, which contributes fluidity and volatility; ''terra lapida'', the solidifying element, which produces fusibility or the binding quality; and ''terra pinguis'', the fatty element, which gives material substance its oily and combustible qualities.<ref name="r9">Partington, J.R. (1937). A Short History of Chemistry. New York: Dover Publications, Inc.</ref> These three earths correspond with Geber’s three principles. A piece of wood, for example, according to Becher, is composed of ash and terra pinguis; when the wood is burnt, the terra pinguis is released, leaving the ash. In other words, in combustion the fatty earth burns away.
In 1661, [[Robert Boyle]] showed that there were more than just four [[classical element]]s as the ancients had assumed.<ref name="boyle" /> The first modern list of chemical elements was given in [[Antoine Lavoisier]]'s 1789 ''Elements of Chemistry'', which contained thirty-three elements, including [[light]] and caloric. By 1818, [[Jöns Jakob Berzelius]] had determined atomic weights for forty-five of the forty-nine accepted elements. [[Dmitri Mendeleev]] had sixty-six elements in his [[periodic table]] of 1869.
From Boyle until the early 20th century, an element was defined as a pure [[chemical substance|substance]] that cannot be decomposed into any simpler substance.<ref name="boyle">{{cite book | first=Robert | last=Boyle | authorlink=Robert Boyle | year=1661 | title=The Sceptical Chymist | location=London }}</ref> Put another way, a chemical element cannot be transformed into other chemical elements by [[chemistry|chemical]] processes. In 1913, [[Henry Moseley]] discovered that the physical basis of the atomic number of the atom was its nuclear charge, which eventually led to the current definition. The current definition also avoids some ambiguities due to [[isotopes]] and [[allotropes]].
By 1919, there were seventy-two known elements.<ref>{{cite book | last=Carey | first=George, W. | year=1914 | title=The Chemistry of Human Life | location=Los Angeles|}}</ref> In 1955, element 101 was discovered and named [[mendelevium]] in honor of Mendeleev, the first to arrange the elements in a periodic manner. In October 2006, the synthesis of element 118 was reported; however, element 117 has not yet been created in the laboratory.
==Description==
The lightest elements are [[hydrogen]] and [[helium]], both created by [[Big Bang nucleosynthesis]] during the [[Timeline of the Big Bang|first 20 minutes of the universe]]<ref>{{cite journal|title=Evidence for Dark Matter|url=http://gaitskell.brown.edu/physics/talks/0408_SLAC_SummerSchool/Gaitskell_DMEvidence_v16.pdf|author=Gaitskell, R|pages=timeline on page 10|accessdate=2008-10-08|doi=10.1103/PhysRevC.74.044602|year=2006|journal=Physical Review C|volume=74}}</ref> in a [[ratio]] of around 3:1 by mass (approximately 12:1 by number of atoms). Almost all other elements found in nature, including some further hydrogen and helium created since then, were made by various natural or (at times) artificial methods of [[nucleosynthesis]], including occasionally by activities such as [[nuclear fission]].
As of 2006, there are 117 known elements (in this context, "known" means observed well enough, even from just a few decay products, to have been differentiated from any other element).<ref>{{cite web | last = Sanderson | first = Katherine | title = Heaviest element made - again | work = nature@news.com | publisher = [[Nature (journal)]] | date = [[17 October]] [[2006]] | url = http://www.nature.com/news/2006/061016/full/061016-4.html | accessdate = 2006-10-19 }}</ref><ref>{{cite web | author = Phil Schewe and Ben Stein | title = Elements 116 and 118 Are Discovered | work = Physics News Update | publisher = [[American Institute of Physics]] | date = [[17 October]] [[2006]] | url = http://www.aip.org/pnu/2006/797.html | accessdate = 2006-10-19 }}</ref> Of these 117 elements, 94 occur naturally on Earth. Six of these occur in extreme trace quantities: [[technetium]], atomic number 43; [[promethium]], number 61; [[astatine]], number 85; [[francium]], number 87; [[neptunium]], number 93; and [[plutonium]], number 94. These 94 elements, and also possibly element 98 [[californium]], have been detected in the universe at large, in the spectra of stars and also supernovae, where short-lived radioactive elements are newly being made.
The remaining 22 elements not found on Earth or in astronomical spectra have been derived artificially. All of the elements that are derived solely through artificial means are radioactive with very short [[half-life|half-lives]]; if any atoms of these elements were present at the formation of Earth, they are extremely likely to have already decayed, and if present in novae, have been in quantities too small to have been noted. [[Technetium]] was the first purportedly non-naturally occurring element to be synthesized, in 1937, although trace amounts of technetium have since been found in nature, and the element may have been discovered naturally in 1925. This pattern of artificial production and later natural discovery has been repeated with several other radioactive naturally occurring trace elements.
Lists of the elements [[List of elements by name|by name]], [[List of elements by symbol|by symbol]], [[List of elements by number|by atomic number]], [[List of elements by density|by density]], [[List of elements by melting point|by melting point]], and [[List of elements by boiling point|by boiling point]] as well as [[Ionization energies of the elements]] are available. The most convenient presentation of the elements is in the [[periodic table]], which groups elements with similar chemical properties together.
===Atomic number===
The [[atomic number]] of an element, ''Z'', is equal to the number of protons which defines the element. For example, all [[carbon]] atoms contain 6 protons in their [[atomic nucleus|nucleus]]; so the atomic number "Z" of carbon is 6. Carbon atoms may have different numbers of neutrons, which are known as [[isotope]]s of the element.
The number of protons in the atomic nucleus also determines its [[electric charge]], which in turn determines the [[electron]]s of the atom in its [[ionization|non-ionized]] state. This in turn (by means of the [[Pauli exclusion principle]]) determines the atom's various [[chemical property|chemical properties]]. So all carbon atoms, for example, ultimately have identical chemical properties because they all have the same number of protons in their nucleus, and therefore have the same atomic number. It is for this reason that atomic number rather than [[mass number]] (or [[atomic weight]]) is considered the identifying characteristic of an element.
===Atomic mass===
The [[mass number]] of an element, ''A'', is the number of [[nucleons]] (protons and neutrons) in the atomic nucleus. Different isotopes of a given element are distinguished by their mass numbers, which are conventionally written as a super-index on the left hand side of the atomic symbol (e.g., <sup>238</sup>U).
The [[relative atomic mass]] of an element is the average of the atomic masses of all the chemical element's isotopes as found in a particular environment, weighted by isotopic abundance, relative to the [[atomic mass unit]] (u). This number may be a fraction which is not close to a whole number, due to the averaging process. On the other hand, the atomic mass of a pure isotope is quite close to its mass number. Whereas the mass number is a natural (or whole) number, the atomic mass of a single isotope is a real number which is close to a natural number. In general, it differs slightly from the mass number as the mass of the protons and neutrons is not exactly 1 u, the electrons also contribute slightly to the atomic mass, and because of the [[nuclear binding energy]]. For example, the mass of <sup>19</sup>F is 18.9984032 u. The only exception to the atomic mass of an isotope not being a natural number is <sup>12</sup>C, which has a mass of ''exactly'' 12, due to the ''definition of u'' (it is fixed as 1/12th of the mass of a free carbon-12 atom, exactly).
=== Isotopes ===
[[Isotope]]s are atoms of the same element (that is, with the same number of protons in their atomic nucleus), but having ''different'' numbers of [[neutron]]s. Most (66 of 94) naturally occurring elements have more than one stable isotope. Thus, for example, there are three main isotopes of [[carbon]]. All carbon atoms have 6 protons in the nucleus, but they can have either 6, 7, or 8 neutrons. Since the mass numbers of these are 12, 13 and 14 respectively, the three isotopes of carbon are known as carbon-12, carbon-13, and carbon-14, often abbreviated to <sup>12</sub>C, <sup>13</sub>C, and <sup>14</sub>C. Carbon in everyday life and in [[chemistry]] is a mixture of <sup>12</sub>C, <sup>13</sub>C, and <sup>14</sub>C atoms.
All three of the isotopes of carbon have the same chemical properties. But they have different nuclear properties. In this example, carbon-12 and carbon-13 are stable atoms, but [[carbon-14]] is unstable; it is slightly [[radioactive]], decaying over time into other elements.
Like carbon, some [[isotopes]] of various elements are [[radioactive]] and decay into other elements upon radiating an alpha or beta particle. For certain elements, all their isotopes are radioactive isotopes: specifically the elements without any stable isotopes are technetium (atomic number 43), promethium (atomic number 61), and all observed elements with [[atomic numbers]] greater than 82.
Of the 80 elements with a stable isotope, 16 have only one stable isotope, and the mean number of stable isotopes for the 80 stable elements is 3.4 stable isotopes per element. The largest number of stable isotopes that occur for an element is 10 (for tin, element 50).
===Allotropes===
Some elements can be found as multiple elementary substances, known as [[allotropes]], which differ in their structure and properties. For example, carbon can be found as [[diamond]], which has a tetrahedral structure around each carbon atom; [[graphite]], which has layers of carbon atoms with a hexagonal structure, and [[fullerene]]s, which have nearly spherical shapes. The ability for an element to exist in one of many structural forms is known as 'allotropy'.
===Standard state===
The [[standard state]], or reference state, of an element is defined as its thermodynamically most stable state at 1 bar at a given temperature (typically at 298.15 K). In [[thermochemistry]], an element is defined to have an [[Standard enthalpy change of formation|enthalpy of formation]] of zero in its standard state. For example, the reference state for carbon is graphite, because it is more stable than the other allotropes.
==Nomenclature==
The naming of elements precedes the atomic theory of matter, although at the time it was not known which chemicals were elements and which compounds. When it was learned, existing names (''e.g.,'' gold, mercury, iron) were kept in most countries, and national differences emerged over the names of elements either for convenience, linguistic niceties, or nationalism. For example, the Germans use "Wasserstoff" for "hydrogen" and "Sauerstoff" for "oxygen", while [[English language|English]] and some [[romance language]]s use "sodium" for "natrium" and "potassium" for "kalium", and the French, Greeks, Portuguese and Poles prefer "azote/azot/azoto" for "nitrogen".
But for international trade, the [[Table of chemical elements|official names]] of the chemical elements both ancient and recent are decided by the [[International Union of Pure and Applied Chemistry]], which has decided on a sort of international English language. That organization has recently prescribed that "aluminium" and "caesium" take the place of the US spellings "aluminum" and "cesium", while the US "sulfur" takes the place of the British "sulphur". But chemicals which are practicable to be sold in bulk within many countries, however, still have national names, and those which do not use the [[Latin alphabet]] cannot be expected to use the IUPAC name. According to IUPAC, the full name of an element is not capitalized, even if it is derived from a proper noun such as the elements [[californium]] or [[einsteinium]] (unless it would be capitalized by some other [[capitalization|rule]]). Isotopes of chemical elements are also uncapitalized if written out: [[carbon-12]] or [[uranium-235]].
In the second half of the twentieth century physics laboratories became able to produce nuclei of chemical elements that have a [[half life]] too short for them to remain in any appreciable amounts. These are also named by IUPAC, which generally adopts the name chosen by the discoverer. This can lead to the controversial question of which research group actually discovered an element, a question which delayed the naming of elements with atomic number of 104 and higher for a considerable time. (See [[element naming controversy]]).
Precursors of such controversies involved the nationalistic namings of elements in the late nineteenth century. For example, ''[[lutetium]]'' was named in reference to Paris, France. The Germans were reluctant to relinquish naming rights to the French, often calling it ''cassiopeium''. The British discoverer of ''[[niobium]]'' originally named it ''columbium,'' in reference to the [[New World]]. It was used extensively as such by American publications prior to international standardization.
==Chemical symbols==
:''For the listing of current and not used [[Chemical symbol]]s, and other symbols that look like chemical symbols, please see [[List of elements by symbol]].''
===Specific chemical elements===
Before chemistry became a science, [[alchemy|alchemists]] had designed arcane symbols for both metals and common compounds. These were however used as abbreviations in diagrams or procedures; there was no concept of atoms combining to form molecules. With his advances in the atomic theory of matter, [[John Dalton]] devised his own simpler symbols, based on circles, which were to be used to depict molecules.
The current system of chemical notation was invented by [[Jöns Jakob Berzelius|Berzelius]]. In this typographical system chemical symbols are not used as mere abbreviations - though each consists of letters of the [[Latin alphabet]] - they are symbols intended to be used by peoples of all languages and alphabets. The first of these symbols were intended to be fully universal; since Latin was the common language of science at that time, they were abbreviations based on the [[Latin]] names of metals - Fe comes from Ferrum, Ag from Argentum. The symbols were not followed by a period (full stop) as abbreviations were. Later chemical elements were also assigned unique chemical symbols, based on the name of the element, but not necessarily in English. For example, [[sodium]] has the chemical symbol 'Na' after the Latin ''natrium''. The same applies to "W" (wolfram) for [[tungsten]], "Hg" (hydrargyrum) for [[Mercury (element)|mercury]], "K" (kalium) for [[potassium]], "Au" (aurum) for [[gold]], "Pb" (plumbum) for [[lead]], and "Sb" (stibium) for [[antimony]].
Chemical symbols are understood internationally when element names might need to be translated. There are sometimes differences; for example, the Germans have used "J" instead of "I" for iodine, so the character would not be confused with a [[roman numeral]].
The first letter of a chemical symbol is always capitalized, as in the preceding examples, and the subsequent letters, if any, are always lower case (small letters).
===General chemical symbols===
There are also symbols for series of chemical elements, for comparative formulas. These are one capital letter in length, and the letters are reserved so they are not permitted to be given for the names of specific elements. For example, an "X" is used to indicate a variable group amongst a class of compounds (though usually a [[halogen]]), while "R" is used for a [[Radical (chemistry)|radical]], meaning a compound structure such as a hydrocarbon chain. The letter "Q" is reserved for "heat" in a chemical reaction. "Y" is also often used as a general chemical symbol, although it is also the symbol of [[yttrium]]. "Z" is also frequently used as a general variable group. "L" is used to represent a general [[ligand]] in inorganic and organometallic chemistry. "M" is also often used in place of a general metal.
===Isotope symbols===
The three main isotopes of the element [[hydrogen]] are often written as H for protium, D for [[deuterium]] and T for [[tritium]]. This is in order to make it easier to use them in chemical equations, as it replaces the need to write out the mass number for each atom. It is written like this:
D<sub>2</sub>O ([[heavy water]])
Instead of writing it like this:
²H<sub>2</sub>O
==The periodic table==
The [[periodic table]] of the chemical elements is a tabular method of displaying the chemical elements. Although precursors to this table exist, its invention is generally credited to [[Russia]]n chemist [[Dmitri Mendeleev]] in 1869. Mendeleev intended the table to illustrate recurring ("periodic") trends in the properties of the elements. The layout of the table has been refined and extended over time, as new elements have been discovered, and new theoretical models have been developed to explain chemical behavior.
The periodic table is now ubiquitous within the academic discipline of chemistry, providing an extremely useful framework to classify, systematize and compare all the many different forms of chemical behavior. The table has also found wide application in physics, biology, engineering, and industry. The current standard table contains 117 confirmed elements as of January 27, 2008 (while element 118 has been synthesized, element 117 has not).
==Abundance==
{{main|Abundance of the chemical elements}}
During the early phases of the [[Big Bang]], [[Big Bang nucleosynthesis|nucleosynthesis]] of hydrogen nuclei resulted in the production of hydrogen and helium isotopes, as well as very minuscule amounts (on the order of 10<sup>-10</sup>) of lithium and beryllium. There is argument about whether or not some boron was produced in the Big Bang, as it has been observed in some very young stars,<ref>[http://query.nytimes.com/gst/fullpage.html?res=9E0CE5D91F3AF937A25752C0A964958260 Hubble Observations Bring Some Surprises - New York Times<!-- Bot generated title -->]</ref> but no heavier elements than boron were produced. As a result, the primordial abundance of atoms consisted of roughly 75% <sup>1</sup>H, 25% <sup>4</sup>He, and 0.01% [[deuterium]].<ref>{{cite web | last = Wright | first = Edward L. | date = [[September 12]], [[2004]] | url = http://www.astro.ucla.edu/~wright/BBNS.html | title = Big Bang Nucleosynthesis | publisher = UCLA Division of Astronomy | accessdate = 2007-02-22 }}</ref> Subsequent enrichment of [[galactic spheroid|galactic halo]]s occurred due to [[Stellar nucleosynthesis]] and [[Supernova nucleosynthesis]].<ref name="synthesis">{{cite journal | author = G. Wallerstein,
I. Iben Jr., P. Parker, A. M. Boesgaard, G. M. Hale, A. E. Champagne, C. A. Barnes, F. KM-dppeler, V. V. Smith, R. D. Hoffman, F. X. Timmes, C. Sneden, R.N. Boyd, B.S. Meyer, D.L. Lambert | title=Synthesis of the elements in stars: forty years of progress | journal=Reviews of Modern Physics | year=1999 | volume=69 | issue=4 | pages=995–1084 | url=http://www.cococubed.com/papers/wallerstein97.pdf | format=pdf | accessdate=2006-08-04 | doi=10.1103/RevModPhys.69.995 }}</ref> However [[intergalactic space]] can still closely resemble the primordial abundance, unless it has been enriched by some means.
The following table shows the twelve most common elements in our galaxy (estimated spectroscopically), as measured in parts per million, by mass.<ref name=croswell">{{cite book | last = Croswell | first = Ken | authorlink = | coauthors = | title = Alchemy of the Heavens | publisher = Anchor | date= February 1996 | location = | pages = | url = http://kencroswell.com/alchemy.html | doi = | id = ISBN 0-385-47214-5}}</ref> Nearby galaxies that have evolved along similar lines have a corresponding enrichment of elements heavier than hydrogen and helium. The more distant galaxies are being viewed as they appeared in the past, so their abundances of elements appear closer to the primordial mixture. As physical laws and processes appear common throughout the [[visible universe]], however, it is expected that these galaxies will likewise have evolved similar abundances of elements.
{|class="wikitable"
|-
!Element!!Parts per million<br />by mass
|-
|[[Hydrogen]]
|739,000
|-
|[[Helium]]
|240,000
|-
|[[Oxygen]]
|10,400
|-
|[[Carbon]]
|4,600
|-
|[[Neon]]
|1,340
|-
|[[Iron]]
|1,090
|-
|[[Nitrogen]]
|960
|-
|[[Silicon]]
|650
|-
|[[Magnesium]]
|580
|-
|[[Sulfur]]
|440
|-
|[[Potassium]]
|210
|-
|[[Nickel]]
|100
|}
==Recently discovered element claims==
The first [[transuranium element]] (element with [[atomic number]] greater than 92) discovered was [[neptunium]] in 1940. As of August 2007, only the elements up to 111, [[Roentgenium]], have been confirmed as valid by [[IUPAC]], while more or less reliable claims have been made for synthesis of elements [[Ununbium|112]], [[Ununtrium|113]], [[Ununquadium|114]], [[Ununpentium|115]], [[Ununhexium|116]] and [[Ununoctium|118]]. The heaviest element that is believed to have been synthesized to date is element 118, [[ununoctium]], on October 9, 2006, by the [[Flerov Laboratory]] of Nuclear Reactions in [[Dubna]], [[Russia]].<ref>{{cite web | author = Phil Schewe and Ben Stein | title = Elements 116 and 118 Are Discovered | work = Physics News Update | publisher = [[American Institute of Physics]] | date = [[17 October]] [[2006]] | url = http://www.aip.org/pnu/2006/797.html | accessdate = 2006-10-19 }}</ref><ref>{{cite journal
| last = Oganessian
| first = Yu. Ts.
| authorlink =
| coauthors = Utyonkov, V.K.; Lobanov, Yu.V.; Abdullin, F.Sh.; Polyakov, A.N.; Sagaidak, R.N.; Shirokovsky, I.V.; Tsyganov, Yu.S.; Voinov, Yu.S.; Gulbekian, G.G.; Bogomolov, S.L.; B. N. Gikal, A. N. Mezentsev, S. Iliev; Subbotin, V.G.; Sukhov, A.M.; Subotic, K; Zagrebaev, V.I.; Vostokin, G.K.; Itkis, M. G.; Moody, K.J; Patin, J.B.; Shaughnessy, D.A.; Stoyer, M.A.; Stoyer, N.J.; Wilk, P.A.; Kenneally, J.M.; Landrum, J.H.; Wild, J.H.; and Lougheed, R.W.
| title = Synthesis of the isotopes of elements 118 and 116 in the <sup>249</sup>Cf and <sup>245</sup>Cm+<sup>48</sup>Ca fusion reactions
| journal = [[Physical Review]] C
| volume = 74
| issue = 4
| pages = 044602
| date = [[2006-10-09]]
| url = http://link.aps.org/abstract/PRC/v74/e044602
| doi = 10.1103/PhysRevC.74.044602
| accessdate = 2006-10-16 }}</ref>
Element 117, [[ununseptium]], has not yet been created or discovered, although its place in the periodic table is preestablished.
According to [[Amnon Marinov]] and six other researchers [[unbibium|element 122]] has been detected naturally occurring in a thorium deposit.<ref name=marinov_6>{{cite journal
| last=Marinov | first=A.
| coauthors=Rodushkin, I.; Kolb, D.; Pape, A.; Kashiv, Y.; Brandt, R.; Gentry, R. V.; Miller, H. W.
| title=Evidence for a long-lived superheavy nucleus with atomic mass number A=292 and atomic number Z=~122 in natural Th
| journal=arXiv.org | year=2008
| url=http://arxiv.org/abs/0804.3869
| accessdate=2008-04-28
| doi=10.1103/PhysRevC.74.044602
| volume=74
| pages=044602 }}</ref>, this is the first Naturally occurring heavy element in more than 50 years. It has yet to be proved as it is still under confirmation by the university but could be a major development as previously all transuranic elements were artificial.
==See also==
<div style="-moz-column-count:2; column-count:2;">
* [[Abundance of the chemical elements]]
* [[Chemical compound|Compound]]
* [[Chemical symbol]]
* [[Chemistry]]
* [[Discovery of the chemical elements]]
* [[Elements song]]
* [[Fictional element]]
* [[Goldschmidt classification]]
* [[Island of stability]]
* [[List of chemical element name etymologies]]
* [[List of elements by atomic number]]
* [[List of elements by name]]
* [[Periodic table]]
* [[Systematic element name]]
* [[Prices of elements and their compounds]]
</div>
==References==
{{reflist}}
*E.R. Scerri, The Periodic Table, Its Story and Its Significance, Oxford University Press, NY, 2007.
==External links==
{{CommonsCat|Chemical elements}}
[[Category:Chemical elements| ]]
[[Category:Chemistry]]
[[af:Chemiese element]]
[[als:Chemisches Element]]
[[ar:عنصر كيميائي]]
[[an:Elemento quimico]]
[[ast:Elementu químicu]]
[[bn:মৌলিক পদার্থ]]
[[zh-min-nan:Hoà-ha̍k goân-sò͘]]
[[be:Хімічны элемент]]
[[be-x-old:Хімічны элемэнт]]
[[bs:Hemijski element]]
[[br:Elfenn gimiek]]
[[bg:Химичен елемент]]
[[ca:Element químic]]
[[cv:Хими элеменчĕсем]]
[[cs:Chemický prvek]]
[[cy:Elfen gemegol]]
[[da:Grundstof]]
[[de:Chemisches Element]]
[[et:Keemiline element]]
[[el:Χημικό στοιχείο]]
[[es:Elemento químico]]
[[eo:Kemia elemento]]
[[eu:Elementu kimiko]]
[[fa:عنصر شیمیایی]]
[[fo:Frumevni]]
[[fr:Élément chimique]]
[[fy:Elemint]]
[[fur:Element chimic]]
[[ga:Dúil cheimiceach]]
[[gl:Elemento químico]]
[[ko:화학 원소]]
[[hi:रासायनिक तत्व]]
[[hr:Kemijski element]]
[[io:Kemia elemento]]
[[id:Unsur kimia]]
[[ia:Elemento chimic]]
[[is:Frumefni]]
[[it:Elemento chimico]]
[[he:יסוד כימי]]
[[jv:Unsur kimia]]
[[kn:ಮೂಲಧಾತು]]
[[ka:ქიმიური ელემენტი]]
[[sw:Elementi za kikemia]]
[[ht:Eleman chimik]]
[[la:Elementum]]
[[lv:Ķīmiskais elements]]
[[lt:Cheminis elementas]]
[[jbo:selratni]]
[[lmo:Element chimich]]
[[hu:Kémiai elem]]
[[mk:Хемиски елемент]]
[[ml:മൂലകം]]
[[mt:Element Kimiku]]
[[ms:Unsur kimia]]
[[mn:Химийн элемент]]
[[nl:Chemisch element]]
[[ne:रसायनिक तत्त्व]]
[[new:तत्त्व(रसायनशास्त्र)]]
[[ja:元素]]
[[no:Grunnstoff]]
[[nn:Grunnstoff]]
[[nrm:Êlément]]
[[nov:Elemente]]
[[oc:Element quimic]]
[[uz:Kimyoviy unsur]]
[[pms:Element chìmich]]
[[nds:Cheemsch Element]]
[[pl:Pierwiastek chemiczny]]
[[pt:Elemento químico]]
[[ro:Element chimic]]
[[qu:Qallawa]]
[[ru:Химический элемент]]
[[sco:Element]]
[[stq:Element]]
[[scn:Elimentu chìmicu]]
[[simple:Chemical element]]
[[sk:Chemický prvok]]
[[sl:Kemični element]]
[[sr:Хемијски елемент]]
[[sh:Kemijski element]]
[[su:Unsur kimia]]
[[fi:Alkuaine]]
[[sv:Grundämne]]
[[tl:Elementong kimikal]]
[[ta:தனிமம்]]
[[th:ธาตุเคมี]]
[[vi:Nguyên tố hóa học]]
[[tr:Element]]
[[uk:Хімічні елементи]]
[[vec:Elemento chimego]]
[[yi:כעמישער עלעמענט]]
[[yo:Àpilẹ̀sẹ̀]]
[[zh-yue:元素]]
[[zh:元素]]