An extremely unreactive gaseous element
occurring in the atmosphere to the extent of 18 parts per million. Neon,
one of the noble gases, is obtained by
the fractional distillation of air. It is colorless but glows reddish-orange
in an electric discharge and is used in fluorescent tubes and gas lasers.
The most common isotope is 20Ne
(90.92%). Neon was discovered in 1898 by Scottish chemist William Ramsay
and English chemist Morris W. Travers.
|Neon tubes. Credit:
Pslawinski & Wikipedia
|relative atomic mass
|In a neon light (A), positively charged ions (1)
strike a negative electrode, causing emission of electrons (2). which
"energize" electrons in neon atoms (3). When the energized electrons
return to their stable, "ground" state (4), red light is emitted.
Similarly, a mercury vapor lamp (B) emits ultraviolet light (5). This
may be absorbed by a fluorescent substance (6), which can then release
the energy in stages (7).