whot3 the we? Neon
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Ne
Symbol: Atomic number: Atomic weigm: Melting point:
24.5 K
~jl;~polnt:
27.1 K
10 20.18
0.0009 g/cm3
Neon (GI: neos, new) is a colorless, odorless, and tasteless gas. While neon is not particularly abundant in the atmosphere (comprising about 18 pL of n e o n b of air), it is-in dry air-three times more abundant than helium (about 5 pL of h e l i u m b of air). The noble gases as a group compose about 1% of our atmosphere. Neon has three stable isotopes (20, 21, and 22) with about 90.5% present as neon-20 and 9.2% as neon-22. Five other isotopes have been reported. The discovery of the inert gas& in our atmosphere ranks among the more interesting stories of elemental discoveries. Sir William Ramsay and Lord Rayleigh were comparing the relative densities of nitrogen isolated from the atmosphere with that of nitrogen isolated from ammonia. The greater density of atmospheric nitrogen led the investigators to separate the nitrogen from the residue. Using magnesium to in August lEg4 Ramsay and Iemove the discovered the element we call areon. In 1898 Ramsav and M, W, Travers fractionally distille&liquid air and discovered krypton. In June of that year, further studies by the two revealed neon as a fraction of a sample of argon, and-one month later-xenon was found in the residue from the distillation of krypton. History records that H. Cavendish had ~~~~~~
588
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Journal of Chemical Education
ALTON
BANKS
SoUmwest Texas State University San Marcos, TX 78666
previously studied the disparity of nitrogen densities hut apparently failed t o follow-up on the work. .. presently neon, argon, krypton, and xenon are collected in air separation plants by liquefaction techniques. Data from 1978 indicates that the yearly consumption of neon is approximately 28,000 m3. The largest single use of neon is-of course-in neon siws. The well-known reddish-oranee elow of the neon sign ;as dramatically changed the f a c e o r t h e earth. The eeneric "neon" sien mav be filled with other inert gases. ~ e l & memits a ye16wish&hite glow, mixtures of neon and areon a lavender hue. T o a much lesser extent, neon has heen used in hyperbaric breathing mixtures and lightning arrestors, as well as high-voltage switching and regulating tubes. Neon and neon-hydrogen mixtures have been used in bubble chambers as well as in lasers-in combination with helium. While liquid neon has been used to cool radiation detectors, the cryogenic uses of neon have grown slowly-due in part to its cost. The liquefied gas has a refrigerating capacity that is greater than that of liquefied helium and is simultaneously less expensive than helium. Some of these applications are shown on "The Periodic Table Videodisc" in frames 36423-36434. "KC? Diamvemr: Exploring the Properties of the Chemical Elementr"; J . Chrm. Edur.: Soft. 1988. lB(1). ffandbaok of ~ h e m i ~ i r y o n~ dh ~ a i e r . 6 8 ed.; t h weat. Robert c., ~ d .chemical ; ~uhbe~: Cleveland, OH; 1971-1972:p 8-25, Kirk-Othmer Enryclopedio a, Chemicol Technology, 2nd ed.: Interscien~e,New York. ,qefi.vn~ $0 ...., . . ., nnii6?.RPS * .. .. . .. McGrau-Hill Encyclopedia of Science and Technology; Parker. S., Ed.; McGraw-Hill: New York. 1977: Vol.9, pp50-51. Mellor,J . , A c,,P,~,,,~o. T~~~~~~on Inorganic and Thaorrficol c ~ P ~Long~ ~ ~ mans, ereen: paris, 1822: VOI.7, pp 88a800.
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