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whcrt3 the we? ALTON BANKS SOUhwest Texas State University San Marcas. TX 78666 Beryllium Symbol: Atomic number: Atomic welght: Melting point: Boiling point: Densitv: Credit for the discovery of beryllium is given to L. Vau- qnelin who, in 1798, found the element in the beryllium aluminum silicate gemstone known as beryl (Be3A12Si6018). Impetus for this discoverv was ~rovided hv a woloeist who hadnoted the similar density, hardness, and eGernA crystal structure of a bervl from Limones and an emerald from Peru. Vauquelin found that both materials were aluminum sili- cates, and contained the previously unknown element, be- ryllium. One should note that emeralds additionally contain approximately 2% Cr as a color center. The element is not particularly ahundant--ahout 0.0005% of the earth's crust- and is usually found in surface deposits of beryl in pegmatite rocks. The most important commercial deposits are found in South America and South Africa. The pure metal was first prepared by F. Wohler in 1828. Indeed Wohler suggested the name--due to thesimilarity with the mineral. An alternative (and rarely found) name for the element, glucinium, is de- rived from the Greek-glykys, sweet-and presents an in- teresting footnote. Beryllium and its compounds are report- ed to possess a sweet taste. The toxicity of these compounds is reportedly due to replacement of magnesium by beryllium in Mg-activated enzymes. Beryllium isanextremely lightweight metal,and theaddi- tion of beryllium to alloys imparts excellent electrical and thermal conductivities. 1ndeed more than twn-thirds of the -----. .- .--. beryllium produced is involved with alloy production. The most im~ortant of these is a Be-Cu allov. Allovs containing " ~~~--~-~- about 2% Be have been used in springsand electrical cog tacts. This nonmagnetic alloy is widely used in the petro- leum industry for sparkproof tools. The high strength and good wear resistance of this allov has eiven it an imnortant place in the building of modern sir- an2 spacecraft. Nickel- beryllium alloys have found similar an~lications. Elemental beryllium is used in x-ray tubes, owing to the transparency of the metal to low energy X-rays. Additional- Iv. hervllium is widelv used in the moderators of nuclear .. . reactors. An interesting aside is that mixtures of compounds of radium and beryllium have been used as a convenient source of neutrons, and indeed led to the discovery of the neutron bv Chadwick in 1932. Some oi' these applications are shown on "The Periodic Table Videodisc" in frames 36339-36344. Sources "KC? Discoverer: Exploring the Properties of the Chemical Elements"; JCE: Sofirnore 1988.18(1). Banks, A. J.; "The Periodic Table Videodise": JCE: Soitwore 1989, Special Issue 1. Hondboob of Chamiatry & Physics, 52th ed.; Weast, Robert C., Ed.; Chemical Rubber: Cleveland, OH: 1971-1972: p 8-7. Kirk-Orhmar concise Encyrlopadio of Chemi<ol Technolog>: Interscience: New York, 1985: pp 164-165. Greenwood, N. N.: Earnahaw. A; Chomisfryof the Elements; Percamon: New York. 1984: ""I>".,", "" . . . .- .. McCraw-Hill Concia8 Encyclopedia o/ Seioneo & Teehnolagy; Parker, S., Ed.: McGraw- Hill: New York, 1881:~ 214. 1018 Journal of Chemical Education
