Neon
Neon is the
chemical element in the periodic table that has the symbol Ne and atomic number 10. A colorless, nearly inert noble gas, neon gives a distinct reddish glow when used in vacuum discharge tubes and
neon lamps and is found in air in trace amounts.
Encyclopedia
Neon is the
chemical element in the periodic table that has the symbol
Ne and atomic number 10. A colorless, nearly inert noble gas, neon gives a distinct reddish glow when used in vacuum discharge tubes and
neon lamps and is found in air in trace amounts.
Notable characteristics
Neon is the second-lightest noble gas, glows
reddish-orange in a vacuum discharge tube and has over 40 times the refrigerating capacity of liquid
helium and three times that of liquid
hydrogen . In most applications it is a less expensive refrigerant than helium. Neon has the most intense discharge at normal voltages and currents of all the rare gases.
Applications
The reddish-orange color that neon emits in
neon lights is widely used to make advertising
signs. The word "neon" is also used generically for these types of lights even though many other gases are used to produce different colors of light. Other uses:
- vacuum tubes
- high-voltage indicators
- lightning arrestors
- wave meter tubes
- television
...
tubes
- Neon and helium are used to make a type of gas laser
- Liquefied neon is commercially used as a cryogenic refrigerant in applications not requiring the lower temperature range attainable with more expensive liquid helium refrigeration.
History
Neon was discovered by Scottish chemist
William Ramsay and English chemist Morris Travers in 1898.
Occurrence
Neon is a monatomic gas at standard conditions. Neon is rare, found in the
Earth's atmosphere at 1 part in 65,000 and industrially produced by cryogenic
fractional distillation of liquified air.
Compounds
The ions, Ne
+,
+,
+, and , have been observed from optical and
mass spectrometric research. In addition, neon forms an unstable hydrate.
Isotopes
Neon has three stable isotopes:
20Ne ,
21Ne and
22Ne .
21Ne and
22Ne are nucleogenic and their variations are well understood. In contrast,
20Ne is not known to be nucleogenic and the causes of its variation in the
Earth have been hotly debated. The principal
nuclear reactions which generate neon isotopes are neutron emission, alpha decay reactions on
24Mg and
25Mg, which produce
21Ne and
22Ne, respectively. The
alpha particles are derived from
uranium-series decay chains, while the
neutrons are mostly produced by secondary reactions from alpha particles. The net result yields a trend towards lower
20Ne/
22Ne and higher
21Ne/
22Ne ratios observed in uranium-rich rocks such as
granites. Isotopic analysis of exposed terrestrial rocks has demonstrated the
cosmogenic production of
21Ne. 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 magmatic neon and nucleogenic neon. This suggests that neon will be a useful tool in determining cosmic exposure ages of surficial rocks and
meteorites.
Similar to
xenon, neon content observed in samples of
volcanic gases are enriched in
20Ne, as well as nucleogenic
21Ne, relative to
22Ne content. The neon isotopic content of these mantle-derived samples represent a non-atmospheric source of neon. The
20Ne-enriched components are attributed to exotic primordial rare gas components in the Earth, possibly representing solar neon. Elevated
20Ne abundances are also found in
diamonds, further suggesting a solar neon reservoir in the Earth.
References
External links
