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Symbol:
u
Atomic number: Atomic weight Melting point: Boiling point: Density:
While evidence exists that compounds of boron were used in the ancient world to make glazes and borosilicate glasses, most sources list the date of discovery for elemental boron as 1808. The discovery is credited to Sir Humphry Davy, J. L. Gav-Lussac. and L. J. Thenard for the isolation of an i m ~ u r e sample. In 1892, H. Moisson obtained samples of 95598% puritv bv reducing.BlOn . .with magnesium. Elemental boron bbtaiied by this method is referred to as Moisson's boron. Davy suggested that the element be named boron to indicate both the source of the element (BORax) and the similarity of the element to carhON. Boron could be considered a rare element as its abundance in the earth's crust is 0.OM)3%. Horon is found in twokajor deposits inTurkey and California. Indeed the world's lareest sinrle source of boron is in Boron, California, where boron is Found in the form of the minerals borax, Na2B407.10 H20, and kernite, Na2Ba07. 4 H20. It should perhaps be noted that boron also accumulates in areas of thermal and volcanic activity as in Tuscany, Italy. ~~
14
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Journal Of Chemical Education
ALTON BANKS SOUmWest TBXBSState University San Marcos, TX 78666
Boron's industrial and domestic uses vary widely. Borosilicates-minerals containing boron, silicon, and oxygen-are used in heat-resistant glasses, glass wool, and fiber glass. These applications provide between 30 and 35% of the element's uses. Detergents, soaps, water-softening agents, and cosmetics use borax, and account for another 15-20% of boron consumption. Boric acid (specificallv orthoboric acid, H3B03) i s w e d as a fire retardant and m a component of welding and brazing fluxes. Powdered boron embedded in polymeric matrices is used as a shield for thermal neutrons in nuclear reactors. Boron compounds are used as synthetic herbicides and fertilizers. Small amounts of boron anoear .. to be essential for plant life, yet boron is toxic to plants in large concentrations. Recent applications of boron revolve around the extremeIv hard. cbemicallv inert. refradorv borides of titanium. 'irconium, and ch;omiu&. These include turbine blades; rocket nozzles, and ablation shields. Finallv, boron fibre composites are being used as reinforcing ma&als in commercial aircraft, golf shafts, tennis rackets, and bicycle frames. Some of these applications are shown on "The Periodic Table Videodisc" in frames 36345-36362. Sources
Pmpeniea of the Chemical Elemmu": JCE. Software Banks,A. J. "The Periodic Table Videodisc': JCE: Sofirnore 1989,Sp~cial Issue 1. Handbook of Chemistry & Physics, 52th ed.: Weast, Robert C.,Ed.:TheChemicalRubher "KC? Disoverer: Explorinp the
1988,1B(l).
Co.: Cleveland, OH, 1971-1872: p B-8. Kirk-0fhm.r Conc& Encyelopedio of Chemicol Teehnolagy, Interscience: New York. 1985: pp 176178. Greanwmd. N. N.; Earnshsw, A. Chemistry of the Elements:Pergamon: New Y a k , 1964: PP 15&163. McCmv-Hill Concise Eneyciopadia ofScirnee & Technology; ParLer. S., Ed.: MeGrawHill: New York, 1964:pp 249252. Muette&s,E. L. The ChemistrvofBoronondita Compounds; Wiley: NewYork. 1967:pp
- ". 7.9
Progres$inBoron Chemistry; Brothenon,R.J.; Steinberg, H., Eds.;Pe.gamon: New York. 1970; Val. 2. pp 260-263.
