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OXYGEN

(Gr. oxys, sharp, acid, genes, forming)

O  at. wt. (natural) 15.999312
   at. no. 8
   m.p. -218.4°C
   b.p. -182.962°C
   density 1.429 gm./l. (0°C)
   sp. gr. liquid 1.14 (- 182.96°C)
   valence 2.
Electronic configuration
 SHELL  K L M N O P Q
 SUB  SHELL He Neon Argon Krypton Xenon Radon Eka-radon
1s 2s 2p 3s 3p 3d 4s 4p 4d 5s 5p 4f 5d 6s 6p 5f 6d 7s 7p
Oxygen 1s22s22p4          
Symbol 3P2
Oxygen. For many centuries, workers from time-to-time realized air was composed of more than one component. The behavior of oxygen and nitrogen as components of air, led to the advancement of the phlogiston theory of combustion, which captured the minds of chemists for a century. Oxygen was prepared by several workers, including Bayen and Borch, but they did not know how to collect it, did not study its properties, nor did they recognize it as an elementary substance. Priestley is generally credited with its discovery, although Scheele also discovered it independently. Oxygen is the third most abundant element found in the sun, and it plays a part in the carbon-nitrogen cycle~ne process thought to give the sun and stars their energy. Oxygen under excited conditions is responsible for the bright-red and yellow-green colors of the aurora. Oxygen, as a gaseous element, forms 21 % of the atmosphere by volume from which it can be obtained by liquefaction and fractional distillation. The element and its compounds make up 49.2 %, by weight, of the earth's crust. About two thirds of the human body, and nine tenths of water is oxygen. In the laboratory it can be prepared by the electrolysis of water or by heating potassium chlorate with manganese dioxide as a catalyst. The gas is colorless, odor- less, and tasteless. The liquid and solid forms are a pale blue color and are strongly paramagnetic. Ozone (03), a highly active allotropic form of oxygen, is formed by the action of an electrical discharge or ultra-violet light on oxygen. Ozone's presence in the atmosphere (amounting to the equivalent of a layer 3 mm thick at ordinary pressures and temperatures) is of vital importance in preventing ultra- violet rays from the sun from reaching the earth's surface and destroying life on earth. Undiluted ozone has a bluish color. Liquid ozone is bluish-black, and solid ozone is violet-black. Oxygen is very reactive and capable of combining with most elements. It is a component of hundreds of thousands of organic compounds. It is essential for respiration ofall plants and animals and for practically all combustion. In hospitals it is frequently used to aid respiration of patients. Its atomic weight was used as a standard of comparison for each of the other elements until 1961 when the International Union of Pure and Applied Chemistry adopted carbon 12 as the new basis. Oxygen has eight isotopes. Natural oxygen is a mixture of three isotopes. Oxygen 18 occurs naturally, is stable, and is available commercially. Water (H20 with 1.5% O'~) is also available. Commercial oxygen consumption in the U.S. is estimated at more than 350 billion cubic feet/year, and the demand is expected to increase substantially in the next few years. Oxygen enrichment of steel blast furnaces ac- counts for the greatest use of the gas. Large quantities are also used in making synthesis gas for ammonia and methan- ol, ethylene oxide, and for oxy-acetylene welding. Air separa- tion plants produce about 99% of the gas; electrolysis plants about 1 %. The gas costs 2.SWcubic foot in small quantities, and from $6 to $12/ton in large quantities.

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