whoti the u m ? ALTON BANKS SoUmwest T e r n State University

San Marcos. TX 78666

Symbol: Li Atomic number: 3 Atomic weight: 6.94 Melting point: 453.7 K Boiling point: 1620.0 K Density: 0.5340 gIcm3

Elemental lithium is a silver-white metal whose density is considerablv less than that of water. Like its analormes in the alkali metal group, lithium is quite reactive and in nature is always found as a mineral or salt. The discovery of lithium in 1817 is credited to Arfwedson, who was analyzing a spodu- mene ore-a lithium aluminum silicate. The findine. of lithi- um in the ore led Arfwedson to select the name From the Greek word for stone-lithos.

Many applications for lithium and its compounds are predicated on the light weight and electrical conductivity of the substances. While lithium hydroxide is used as an addi- tive to the electrolyte for nickel-cadmium batteries, the free metal has been used as an anode in batteries where weight and shelf life are important-in flashlights, watches, and nacemakers. Aluminum-lithium allovs have been used as weight-saving materials in aircraft.

Additionally, lithium-based greases are widely used due to

their retention of lubricating properties over a wide tem- perature range. Lithium carbonate has been used to treat manic-depressive psychosis. Lithium hydroxide is used in emergency breathing equipment to scrub carhon dioxide from the air. Lithium hvnochlorite is used in a wide varietv - - ". of bleaching applications-from swimming pool sanitizers to commercial laundries. Lithium chloride and bromide are used in industrial air conditioning systems to absorb water. Moreover. oreano-lithium com~ounds are useful in the for- mation of several polymers, for &ample, styrene and butadi- ene.

Some of these applications are shown on "The Periodic Table Videodisc" in frames 36321-36338.

Sources The Lithium Corporation of America (LITHCO). Gastonia, NC. Hondbwk a/ Chemistry & Phyaiea. 47th ed.; The Chemical Rubber Ca.: Cleveland. OH.

1966. "KC? Discoverer Exploring the Propertics of the Chemical Elements", JCE: SoJtwre

1988,1.9(1). Benh, A. J. "The Peridic Table Vidwdiic", JCE: Software 1989. SpecialIssue 1

This column will describe certain uses w applications of Um e le ments. h will rot be an exhaustive treatise, but will point out some of me interesting ways in which we employ me elements and/or their compounds. in each ase , a reference to the locations of mese applications on "me Periodic Table Viddisc" will be given. "The briodic Table Viddisc" may be obtained from X E : Software. De- partment of Chemisby. University of Wisconsin, Madison, WI 53706.

Volume 66 Number 9 September 1989 745