Editing Neon (section)

==Chemistry==
[[File:Ne-water clathrate.png|thumb|Crystal structure of Ne [[clathrate hydrate]]<ref name="hydrate" />|300x300px]]
{{main|Neon compounds}}
Neon is the first [[p-block]] noble gas and the first element with a true octet of electrons. It is [[Chemically inert|inert]]: as is the case with its lighter analog, [[helium]], no strongly bound neutral [[Neon compounds|molecules containing neon]] have been identified. An example of neon compound is Cr(CO)<sub>5</sub>Ne, which contains a very weak Ne-Cr bond.<ref>{{cite journal|last1=Perutz|first1=Robin N.|last2=Turner|first2=James J. |title=Photochemistry of the Group 6 hexacarbonyls in low-temperature matrices. III. Interaction of the pentacarbonyls with noble gases and other matrices|journal=Journal of the American Chemical Society|date=August 1975|volume=97|issue=17|pages=4791–4800 |doi=10.1021/ja00850a001|bibcode=1975JAChS..97.4791P }}</ref> The [[ion]]s [Ne[[argon|Ar]]]<sup>+</sup>, [Ne[[hydrogen|H]]]<sup>+</sup>, and [HeNe]<sup>+</sup> have been observed from optical and [[mass spectrometry|mass spectrometric]] studies.<ref name="CRC" /> Solid neon [[clathrate hydrate]] was produced from water ice and neon gas at pressures 350–480&nbsp;MPa and temperatures about −30&nbsp;°C.<ref>{{cite journal |doi=10.1073/pnas.1410690111 |pmid=25002464 |pmc=4115495 |year=2014 |last1=Yu |first1=X. |title=Crystal structure and encapsulation dynamics of ice II-structured neon hydrate |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=111 |issue=29 |pages=10456–61 |last2=Zhu |first2=J. |last3=Du |first3=S. |last4=Xu |first4=H. |last5=Vogel |first5=S. C. |last6=Han |first6=J. |last7=Germann |first7=T. C. |last8=Zhang |first8=J. |last9=Jin |first9=C. |last10=Francisco |first10=J. S. |last11=Zhao |first11=Y. |bibcode=2014PNAS..11110456Y|doi-access=free }}</ref> Ne atoms are not bonded to water and can freely move through this material. They can be extracted by placing the clathrate into a vacuum chamber for several days, yielding [[ice XVI]], the least dense crystalline form of water.<ref name="hydrate">{{cite journal |doi=10.1038/nature14014 |pmid=25503235 |title=Formation and properties of ice XVI obtained by emptying a type sII clathrate hydrate |journal=Nature |volume=516 |issue=7530 |pages=231–3 |year=2014 |last1=Falenty |first1=Andrzej |last2=Hansen |first2=Thomas C. |last3=Kuhs |first3=Werner F. |bibcode=2014Natur.516..231F|s2cid=4464711 }}</ref>

The familiar [[Electronegativity#Pauling electronegativity|Pauling electronegativity scale]] relies upon chemical bond energies, but such values have obviously not been measured for inert helium and neon. The [[Electronegativity#Allen electronegativity|Allen electronegativity scale]], which relies only upon (measurable) atomic energies, identifies neon as the most electronegative element, closely followed by fluorine and helium.<ref>{{cite journal |doi=10.1021/ja00207a003 |title=Electronegativity is the average one-electron energy of the valence-shell electrons in ground-state free atoms|year=1989|author=Allen, Leland C.|journal=Journal of the American Chemical Society |volume=111|pages=9003–9014 |issue=25|bibcode=1989JAChS.111.9003A }}</ref>

The [[triple point]] temperature of neon (24.5561&nbsp;K) is a defining fixed point in the [[International Temperature Scale of 1990]].<ref name="ITS90-1">{{cite web |url=http://www.its-90.com/ |title=The Internet resource for the International Temperature Scale of 1990 |access-date=7 July 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090815110916/http://www.its-90.com/ |archive-date=15 August 2009}}</ref>