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{{Infobox neon}}
'''Neon''' ({{pronEng|ˈniːɒn}}) is the [[chemical element]] that has the symbol '''Ne''' and [[atomic number]] 10. A very common element in the universe, it is rare on Earth. A colorless, [[inert]] [[noble gas]] under standard conditions, neon gives a distinct reddish glow when used in vacuum discharge tubes and [[neon lamp]]s. It is commercially extracted from air, in which it is found in trace amounts.

== History ==
{{Expand-section|date=December 2007}}
Neon ([[Greek language|Greek]] ''νέον''(''neon'') meaning "new one") was discovered in 1898 by Scottish chemist [[William Ramsay]] (1852 - 1916) and English chemist [[Morris W. Travers]] in [[London]], [[England]].<ref>{{cite journal 
 | title = On the Companions of Argon
 | author = [[William Ramsay]], Morris W. Travers 
 | journal = Proceedings of the Royal Society of London 
 | volume = 63
 | issue = 
 | pages = 437-440
 | year = 1898
 | url = http://links.jstor.org/sici?sici=0370-1662%281898%2963%3C437%3AOTCOA%3E2.0.CO%3B2-E}}</ref> Neon was discovered when Ramsay chilled a sample of the atmosphere until it became a liquid, then warmed the liquid and captured the gases as they boiled off. The three gases were [[krypton]], [[xenon]], and neon.<ref>{{cite web |url=http://nautilus.fis.uc.pt/st2.5/scenes-e/elem/e01000.html |title=Neon: History|accessdate=2007-02-27|publisher=Softciências}}</ref>

== Isotopes ==
{{main|Isotopes of neon}}
Neon has three [[stable isotope]]s: <sup>20</sup>Ne (90.48%), <sup>21</sup>Ne (0.27%) and <sup>22</sup>Ne (9.25%). <sup>21</sup>Ne and <sup>22</sup>Ne are [[Nuclear reaction|nucleogenic]] and their variations are well understood. In contrast, <sup>20</sup>Ne is not known to be nucleogenic and the causes of its variation in the [[Earth]] have been hotly debated. The principal [[nuclear reaction]]s which generate neon [[isotope]]s are [[neutron emission]], [[alpha decay]] reactions on <sup>24</sup>Mg and <sup>25</sup>Mg, which produce <sup>21</sup>Ne and <sup>22</sup>Ne, respectively. The [[alpha particle]]s are derived from [[uranium]]-series [[decay chain]]s, while the [[neutron]]s are mostly produced by secondary reactions from alpha particles. The net result yields a trend towards lower <sup>20</sup>Ne/<sup>22</sup>Ne and higher <sup>21</sup>Ne/<sup>22</sup>Ne ratios observed in uranium-rich rocks such as [[granite]]s. Isotopic analysis of exposed terrestrial [[rock (geology)|rocks]] has demonstrated the [[cosmogenic]] production of <sup>21</sup>Ne. This isotope is generated by [[spallation]] reactions on [[magnesium]], [[sodium]], [[silicon]], and [[aluminium]]. By analyzing all three isotopes, the cosmogenic component can be resolved from [[magma]]tic neon and nucleogenic neon. This suggests that neon will be a useful tool in determining cosmic [[exposure age]]s of surficial rocks and [[meteorite]]s.<ref>{{cite web |url=http://nautilus.fis.uc.pt/st2.5/scenes-e/elem/e01093.html |title=Neon: Isotopes|accessdate=2007-02-27|publisher=Softciências}}</ref>

Similar to [[xenon]], neon content observed in samples of [[volcano|volcanic]] [[gas]]es are enriched in <sup>20</sup>Ne, as well as nucleogenic <sup>21</sup>Ne, relative to <sup>22</sup>Ne content. The neon isotopic content of these mantle-derived samples represent a non-atmospheric source of neon. The <sup>20</sup>Ne-enriched components are attributed to exotic primordial rare gas components in the Earth, possibly representing [[solar neon]]. Elevated <sup>20</sup>Ne abundances are found in [[diamond]]s, further suggesting a solar neon reservoir in the Earth.<ref>{{cite web |url=http://www.mantleplumes.org/Ne.html |title=Helium, Neon & Argon|accessdate=2006-07-02|author=Anderson, Don L.|publisher=Mantleplumes.org}}</ref>


== Notable characteristics ==

Neon is the second-lightest [[noble gas]], glows [[red]]dish-[[Orange (colour)|orange]] in a [[discharge tube|vacuum discharge tube]] and has over 40 times the refrigerating capacity of liquid [[helium]] and three times that of liquid [[hydrogen]] (on a per unit volume basis).<ref>{{cite web |url=http://periodic.lanl.gov/elements/10.html |title=Neon |accessdate=2007-03-05 |date=15 |year=2003 |month=12 |format= |work= |publisher=Los Almos National Laboratory |pages= |language=English |archiveurl= |archivedate= |quote= }}</ref> In most applications it is a less expensive [[refrigerant]] than helium.<ref>{{cite web |url=http://www.nassmc.org/bulletin/dec05bulletin.html#table |title=NASSMC: News Bulletin |accessdate=2007-03-05 |date=30 |year=2005 |month=12 |format= |work= |publisher= |pages= |language=English |archiveurl= |archivedate= |quote= }}</ref> Neon plasma has the most intense light discharge at normal voltages and currents of all the rare gases. The average color of this light to the human eye is red-orange; it contains a strong green line which is hidden, unless the visual components are dispersed by a spectroscope.<ref>{{cite web |url=http://www.electricalfun.com/plasma.htm |title=Plasma |accessdate=2007-03-05}}</ref>

== Occurrence ==
Neon is actually abundant on a universal scale: the fifth most abundant chemical element in the universe by mass, after hydrogen, helium, oxygen, and carbon (see [[chemical element]]). Its relative rarity on Earth, like that of helium, is due to its relative lightness and chemical inertness, both properties keeping it from being trapped in the condensing gas and dust clouds of the formation of smaller and warmer solid planets like Earth. Mass abundance in the universe is about 1 part in 750 and in the Sun and presumably in the proto-solar system nebula, about 1 part in 600. The [[Galileo spacecraft]] atmospheric entry probe found that even in the upper atmosphere of Jupiter, neon is reduced by about a factor of 10, to 1 part in 6,000 by mass. This may indicate that even the ice-planetesmals which brought neon into Jupiter from the outer solar system, formed in a region which was too warm for them to have kept their neon (abundances of heavier inert gases on Jupiter are several times that found in the Sun).<ref>{{cite web |url=http://www2.jpl.nasa.gov/sl9/gll38.html |title=Galileo Probe Science Result |accessdate=2007-02-27 |last=Morse |first= David |authorlink= |coauthors= |date=26 |year=1996 |month=01 |format= |work= |publisher=Galileo Project |pages= |language=English |archiveurl= |archivedate= |quote= }}</ref>

Neon is a [[monatomic]] [[gas]] at [[standard conditions]]. Neon is rare on Earth, found in the [[Earth's atmosphere]] at 1 part in 65,000 (by volume) or 1 part in 83,000 by mass. It is industrially produced by cryogenic [[fractional distillation]] of liquefied air.<ref>{{cite web |url=http://www-d0.fnal.gov/hardware/cal/lvps_info/engineering/elements.pdf |title=The Elements |accessdate=2007-02-27 |last=Hammond |first=C. R. |authorlink= |coauthors= |date= |year= |month= |format= |work= |publisher=Fermi National Accelerator Lab|pages=19 |language=English |archiveurl= |archivedate= |quote= }}
</ref>

== Applications ==
[[Image:NeTube.jpg|thumb|left|Neon is often used in [[neon sign|signs]] and produces an unmistakable bright orange colored light. All other colors (though still referred to as "neon") are created using a mercury vapor discharge which excites a [[phosphor]] via [[fluorescence]], or by the other [[Noble Gases]].]]
The reddish-orange color that neon emits in [[Neon lamp|neon light]]s is widely used to make advertising [[neon sign|signs]] and is used in long tubular strips in car modification. The word "neon" is used generically for these types of lights even though many other gases are used to produce different colors of light.

Neon may also be used in [[vacuum tube]]s, high-voltage indicators, [[lightning]] arrestors, wave meter tubes, [[television]] tubes, and [[helium-neon laser]]s. Liquefied neon is commercially used as a [[cryogenic]] [[refrigerant]] in applications not requiring the lower temperature range attainable with more expensive liquid helium refrigeration.

Neon's [[triple point]] temperature of 24.5561 K is a defining fixed point in the [[International Temperature Scale of 1990]].<ref name="ITS90">"[http://www.its-90.com/ The Internet resource for the International Temperature Scale of 1990.]." ''[http://www.its-90.com/legal.html Amazon.com].'' 1999. Retrieved on [[August 31]], [[2007]].</ref>

== Compounds ==
Neon is a [[noble gas]], and therefore generally considered to be [[inert]]. However, the [[ion]]s, Ne<sup>+</sup>, (Ne[[argon|Ar]])<sup>+</sup>, (Ne[[hydrogen|H]])<sup>+</sup>, and ([[helium|He]]Ne<sup>+</sup>), have been observed from optical and [[mass spectrometry|mass spectrometric]] studies, and neon is also known to form an unstable [[hydrate]].<ref name="LANL">"[http://periodic.lanl.gov/elements/10.html Periodic Table: Neon]." ''[[Lawrence Livermore National Laboratory]].'' Last updated on [[December 15]], [[2003]]. Retrieved on [[August 31]], [[2007]].</ref>

== References ==
{{reflist|2}}

== External links ==
{{Commons|Neon}}
{{wiktionary|neon}}
* [http://www.webelements.com/webelements/elements/text/Ne/index.html WebElements.com &ndash; Neon]
* [http://education.jlab.org/itselemental/ele010.html It's Elemental &ndash; Neon]
* [http://www.compchemwiki.org/index.php?title=Neon Computational Chemistry Wiki]
* [http://periodic.lanl.gov/elements/10.html Los Alamos National Laboratory &ndash; Neon]
* [http://wwwrcamnl.wr.usgs.gov/isoig/period/ne_iig.html USGS Periodic Table - Neon]

[[Category:Neon| ]]
[[Category:Chemical elements]]
[[Category:Coolants]]
[[Category:Noble gases]]
[[Category:Refrigerants]]
[[Category:Laser gain media]]

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