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(Latin, neonum), Ne, a chemical element of Group VIII in the Mendeleev periodic system. An inert gas: atomic number, 10; atomic weight, 20.179. On earth it is found mainly in the atmosphere, which is estimated to contain 7.1 × 1011 tons of neon. The neon content of air is about 16 cm3/m3. Atmospheric neon is a mixture of three stable isotopes—20Ne, 21Ne, and 22Ne; the first isotope predominates (90.92 percent). Neon was discovered in 1898 by the British scientists W. Ramsay and M. Travers during their study of the highly volatile fraction of liquid air. The name “neon” is derived from the Greek neos, “new.”
Under ordinary conditions, neon is a colorless, odorless gas. At 0°C and 760 mm of mercury (101 kilonewtons per sq m), the density of neon is 0.900 g/l; melting point, —248.6°C; boiling point, -245.9°C (at 101 KN/m2); solubility in water, 10.4 ml/l. Solid neon has a cubic crystal lattice; the lattice constant a of the unit cell is 4.52 angstroms at —253°C. The neon molecule is monatomic; the outer electron shell of the neon atom contains eight electrons and is highly stable. Neon compounds have not yet been synthesized.
Neon is produced by the fractionation of air. Its largest single use is in electrical engineering. Neon-filled lamps emitting red light are used at harbors, airports, and other locations. Liquid neon is coming to be used in the production of low temperatures.