what5 the we? oxygen
EfB33Em
Symbol: Atomic number: ~tomicweight: Meltlng point: oiling paint: Density:
0 8 16.00 54.8 K 90.2 K 0.0014 g/cm3
Oxygen composes about 21% (by volume) of our atmosphere, about 89%of our water, and about 49%of the sand and rocks, thus earning a place as one of the most important elements. Thestory oftbe identification (discovery ? I of the element is an intereatingone that merits a few words. Hoefer in his work Hivtoire de la chimie noted one early citation of Zosimus (4th Century), "Take the soul of copper which is borne upon the water of mercury, and disengage an aeriform body", as one observation of the evolution of a gas (oxygen) when a compound was heated over mercury. Several person-Eck de Sultzbach, Borrichius, Cardan, and Bayen to name but f o ~ r - ~ r e ~ a r eoxygen, d but did not recognize its elemental character. In 1773 C. W. Scheele noted a substance (feuerluft, fire-air) formed when "nitre was heated with sulphuric acid". History records the unfortunate fact that Scheele's publisher failed to formally print notice of the event until 1777. In 1774 Joseph Priestley prepared "dephlogisticated air" by heating mercuric oxide-among other things-in a cylinder inverted over mercury. Mellor has noted that Priestley thought that the substance evolved was a compound of nitric acid and earth. Lavoisier deduced the nature of this gas and' in 1775' coined the name oxygen (Gr.oxys, 8our;gene.s. forming) believing the element to he an essential part of all acids.
298
Journal of Chemical Education
ALTON J. BANKS Southwest T e a s State University San Marws. TX 78666
The free element, usually separated from other atmospheric components by liquefaction, is an important part of industry-being the fifth largest volume chemical in the United States in 1987. Oxygen possesses three naturally occurring isotopes (160, 170,and '80) and reacts with every other element except helium, neon, and argon. This colorless, odorless, tasteless gas condenses a t -183 OC to form a pale-blue paramagnetic liquid. The triatomic form of oxygen, ozone, was first identified and aptly named (Gr.ozein, to smell) by C. F. Schonbein in 1840. The importance of the ozone layer in the upper atmosphere to life on the earth's surface has recently begun to he a consideration in many arenas. Elemental oxygen is used in several industrial areas: the Bessemer process in steelmaking, blast f u m a c e e i n which the use of Dure oxveen s use of less-ex~ensivefuel .., ~. e r m i tthe oil-and smelting operations. The chemical inhustry uses oxveen .., for controlled oxidations of many materials, for example, ethylene to ethylene oxide. The element is also crucial in the production of synthesis gas (H2 and CO), in the of sewage, in providinga life&staining atmosphere for mining or underwater work, in assisting respiration (oxygen tents), and-most recently-providing fuel for rockets. s shown on "The Periodic Some of these a ~ ~ l i c a t i o nare Table Videodisc" in frames 36399-36410. ~
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General References "KC? Discoverer: Exploring the Properties of the Chemical Elements': JCE: Software 1988, ih I f Il
