Editing Noble gas (section)

==History==
''Noble gas'' is translated from the [[German language|German]] noun {{lang|de|Edelgas}}, first used in 1900 by [[Hugo Erdmann]]<ref>{{cite journal|journal=[[Science (journal)|Science]]|year=1901|volume=13|pages=268–270|last=Renouf|first=Edward|title=Noble gases|doi=10.1126/science.13.320.268|issue=320|bibcode= 1901Sci....13..268R |s2cid=34534533|url=https://archive.org/details/lehrbuchderanor01erdmgoog/page/78/mode/2up}}</ref> to indicate their extremely low level of reactivity. The name makes an analogy to the term "[[noble metal]]s", which also have low reactivity. The noble gases have also been referred to as ''[[inert gas]]es'', but this label is deprecated as many [[noble gas compound]]s are now known.<ref>{{harvnb|Ozima|2002|p=30}}</ref> ''Rare gases'' is another term that was used,<ref>{{harvnb|Ozima|2002|p=4}}</ref> but this is also inaccurate because [[argon]] forms a fairly considerable part (0.94% by volume, 1.3% by mass) of the [[Earth's atmosphere]] due to decay of radioactive [[potassium-40]].<ref>{{cite encyclopedia|encyclopedia=[[Encyclopædia Britannica]]|year=2008|title=argon|url=https://www.britannica.com/eb/article-9009382/argon}}</ref>
[[File:Helium spectrum.jpg|thumb|left|300px|Helium was first detected in the Sun due to its characteristic [[spectral line]]s.|alt=A line spectrum chart of the visible spectrum showing sharp lines on top.]]

[[Pierre Janssen]] and [[Joseph Norman Lockyer]] had discovered a new element on 18 August 1868 while looking at the [[chromosphere]] of the [[Sun]], and named it [[helium]] after the Greek word for the Sun, {{lang|grc|ἥλιος}} ({{lang|grc-Latn|hḗlios}}).<ref>''Oxford English Dictionary'' (1989), s.v. "helium". Retrieved 16 December 2006, from Oxford English Dictionary Online. Also, from quotation there: Thomson, W. (1872). ''Rep. Brit. Assoc.'' xcix: "Frankland and Lockyer find the yellow prominences to give a very decided bright line not far from D, but hitherto not identified with any terrestrial flame. It seems to indicate a new substance, which they propose to call Helium."</ref> No chemical analysis was possible at the time, but helium was later found to be a noble gas. Before them, in 1784, the English chemist and physicist [[Henry Cavendish]] had discovered that air contains a small proportion of a substance less reactive than [[nitrogen]].<ref name="Ozima 1">{{harvnb|Ozima|2002|p=1}}</ref> A century later, in 1895, [[John Strutt, 3rd Baron Rayleigh|Lord Rayleigh]] discovered that samples of nitrogen from the air were of a different [[density]] than nitrogen resulting from [[chemical reaction]]s. Along with Scottish scientist [[William Ramsay]] at [[University College, London]], Lord Rayleigh theorized that the nitrogen extracted from air was mixed with another gas, leading to an experiment that successfully isolated a new element, argon, from the Greek word {{lang|grc|ἀργός}} ({{lang|grc-Latn|argós}}, "idle" or "lazy").<ref name="Ozima 1" /> With this discovery, they realized an entire class of [[gas]]es was missing from the periodic table. During his search for argon, Ramsay also managed to isolate helium for the first time while heating [[cleveite]], a mineral. In 1902, having accepted the evidence for the elements helium and argon, [[Dmitri Mendeleev]] included these noble gases as group&nbsp;0 in his arrangement of the elements, which would later become the periodic table.<ref>{{harvnb|Mendeleev|1903|p=497}}</ref>

Ramsay continued his search for these gases using the method of [[fractional distillation]] to separate [[liquid air]] into several components. In 1898, he discovered the elements [[krypton]], [[neon]], and [[xenon]], and named them after the Greek words {{lang|grc|κρυπτός}} ({{lang|grc-Latn|kryptós}}, "hidden"), {{lang|grc|νέος}} ({{lang|grc-Latn|néos}}, "new"), and {{lang|grc|ξένος}} ({{lang|grc-Latn|ksénos}}, "stranger"), respectively. [[Radon]] was first identified in 1898 by [[Friedrich Ernst Dorn]],<ref>{{cite journal|title=Discovery of Radon|last=Partington|first=J. R.|journal=[[Nature (journal)|Nature]]|volume=179|issue=4566|pages=912|year=1957|doi=10.1038/179912a0|bibcode=1957Natur.179..912P|s2cid=4251991|doi-access=free}}</ref> and was named ''radium emanation'', but was not considered a noble gas until 1904 when its characteristics were found to be similar to those of other noble gases.<ref name="brit">{{cite encyclopedia|encyclopedia=[[Encyclopædia Britannica]]|year=2008|title=Noble Gas|url=https://www.britannica.com/eb/article-9110613/noble-gas}}</ref> Rayleigh and Ramsay received the 1904 [[Nobel Prize]]s in Physics and in Chemistry, respectively, for their discovery of the noble gases;<ref>{{cite web |title=The Nobel Prize in Physics 1904 Presentation Speech |author=Cederblom, J. E. |year=1904 |url=http://nobelprize.org/nobel_prizes/physics/laureates/1904/press.html}}</ref><ref name=nobelchem>{{cite web |title=The Nobel Prize in Chemistry 1904 Presentation Speech |author=Cederblom, J. E. |year=1904 |url=http://nobelprize.org/nobel_prizes/chemistry/laureates/1904/press.html}}</ref> in the words of J. E. Cederblom, then president of the [[Royal Swedish Academy of Sciences]], "the discovery of an entirely new group of elements, of which no single representative had been known with any certainty, is something utterly unique in the history of chemistry, being intrinsically an advance in science of peculiar significance".<ref name=nobelchem/>

The discovery of the noble gases aided in the development of a general understanding of [[Atomic theory|atomic structure]]. In 1895, French chemist [[Henri Moissan]] attempted to form a reaction between [[fluorine]], the most [[electronegativity|electronegative]] element, and argon, one of the noble gases, but failed. Scientists were unable to prepare compounds of argon until the end of the 20th century, but these attempts helped to develop new theories of atomic structure. Learning from these experiments, Danish physicist [[Niels Bohr]] proposed in 1913 that the [[electron]]s in atoms are arranged in [[electron shell|shells]] surrounding the [[atomic nucleus|nucleus]], and that for all noble gases except helium the outermost shell always contains eight electrons.<ref name="brit" /> In 1916, [[Gilbert N. Lewis]] formulated the ''[[octet rule]]'', which concluded an octet of electrons in the outer shell was the most stable arrangement for any atom; this arrangement caused them to be unreactive with other elements since they did not require any more electrons to complete their outer shell.<ref>{{cite journal |author1=Gillespie, R. J. |author2=Robinson, E. A. |title=Gilbert N. Lewis and the chemical bond: the electron pair and the octet rule from 1916 to the present day |journal=J Comput Chem |volume=28 |issue=1 |pages=87–97 |year=2007 |pmid=17109437 |doi=10.1002/jcc.20545|doi-access=free }}</ref>

In 1962, [[Neil Bartlett (chemist)|Neil Bartlett]] discovered the first chemical compound of a noble gas, [[xenon hexafluoroplatinate]].<ref name="bartlett">{{cite journal|title=Xenon hexafluoroplatinate Xe<sup>+</sup>[PtF<sub>6</sub>]<sup>−</sup>|last=Bartlett|first=N.|journal=[[Proceedings of the Chemical Society]]|issue=6|page=218|year=1962|doi=10.1039/PS9620000197}}</ref> Compounds of other noble gases were discovered soon after: in 1962 for radon, [[radon difluoride]] ({{chem|Rn||F|2}}),<ref>{{cite journal|author1=Fields, Paul R. |author2=Stein, Lawrence |author3=Zirin, Moshe H. |title=Radon Fluoride|journal=[[Journal of the American Chemical Society]]|year=1962|volume=84|issue=21|pages=4164–4165|doi=10.1021/ja00880a048|bibcode=1962JAChS..84.4164F }}</ref> which was identified by radiotracer techniques and in 1963 for krypton, [[krypton difluoride]] ({{chem|Kr||F|2}}).<ref>{{cite journal|author1=Grosse, A. V. |author2=Kirschenbaum, A. D. |author3=Streng, A. G. |author4=Streng, L. V. |title=Krypton Tetrafluoride: Preparation and Some Properties|journal=Science|year=1963|volume=139|pages=1047–1048|doi=10.1126/science.139.3559.1047|pmid=17812982|issue=3559|bibcode=1963Sci...139.1047G}}</ref> The first stable compound of argon was reported in 2000 when [[argon fluorohydride]] (HArF) was formed at a temperature of {{convert|40|K}}.<ref>{{cite journal|title=A stable argon compound|journal=[[Nature (journal)|Nature]]|issue= 6798|pages=874–876|year=2000|doi=10.1038/35022551|author1=Khriachtchev, Leonid |author2=Pettersson, Mika |author3=Runeberg, Nino |author4=Lundell, Jan |author5=Räsänen, Markku |volume=406|pmid=10972285 |bibcode=2000Natur.406..874K|s2cid=4382128}}</ref>

In October 2006, scientists from the Joint Institute for Nuclear Research and [[Lawrence Livermore National Laboratory]] successfully created synthetically [[oganesson]], the seventh element in group&nbsp;18,<ref>{{cite journal|journal=Pure Appl. Chem.|volume=83|issue=7|year=2011|title=Discovery of the elements with atomic numbers greater than or equal to 113 (IUPAC Technical Report)*|author1=Barber, Robert C. |author2=Karol, Paul J. |author3=Nakahara, Hiromichi |author4=Vardaci, Emanuele |author5=Vogt, Erich W. |name-list-style=amp |url=http://iupac.org/publications/pac/pdf/2011/pdf/8307x1485.pdf|access-date=30 May 2014|publisher=IUPAC|doi=10.1515/ci.2011.33.5.25b }}</ref> by bombarding [[californium]] with calcium.<ref>{{cite journal |last1=Oganessian |first1=Yu. Ts. |title=Synthesis of the isotopes of elements 118 and 116 in the {{SimpleNuclide |Californium |249}} and {{SimpleNuclide |Curium |245}} + {{SimpleNuclide |Calcium |48}} fusion reactions |journal=Physical Review C |volume=74 |issue=4 |page=44602 |year=2006 |doi=10.1103/PhysRevC.74.044602 |last2=Utyonkov |first2=V. |last3=Lobanov |first3=Yu. |last4=Abdullin |first4=F. |last5=Polyakov |first5=A. |bibcode=2006PhRvC..74d4602O |display-authors=5 |last6=Shirokovsky |first6=I. |last7=Tsyganov |first7=Yu. |last8=Voinov |first8=A. |last9=Gulbekian |first9=G. |last10=Bogomolov |first10=S. |last11=Gikal |first11=B. |last12=Mezentsev |first12=A. |last13=Iliev |first13=S. |last14=Subbotin |first14=V. |last15=Sukhov |first15=A. |last16=Subotic |first16=K. |last17=Zagrebaev |first17=V. |last18=Vostokin |first18=G. |last19=Itkis |first19=M. |last20=Moody |first20=K. |last21=Patin |first21=J. |last22=Shaughnessy |first22=D. |last23=Stoyer |first23=M. |last24=Stoyer |first24=N. |last25=Wilk |first25=P. |last26=Kenneally |first26=J. |last27=Landrum |first27=J. |last28=Wild |first28=J. |last29=Lougheed |first29=R.|doi-access=free }}
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