Li; at. wt 6.941; at. no. 3; valence 1; Alkali metal. Occurence in earth's crusts: 0.005% by wt. Natural isotopes: 7 (92.58%); 6 (7.42%); artificial radioactive isotopes: 5, 8, 9; all are unstable (T˝ < 1 sec). Discovered as salt in 1817 by Arfvedson: Ann. Chim. Phys. [2] 10, 82 (1819); metal prepared independently by Davy and Brandé in 1818. Occurs in a number of minerals; spodumene (LiAlS2O6), lepidolite [K(Li,Al)3(Si,Al)4O10(F,OH)2], petalite (LiAlSi4O10), amblygonite (AlPO4,LiF), and triphylite (LiFePO4) contain 3-10% Li2O. Also recovered from natural brines. Prepn of the metal by electrochemical processes: Guntz, Compt. Rend. 117, 732 (1893); Ruff, Johannsen, Z. Electrochem. 12, 186 (1906); by reduction of the oxide with magnesium or aluminum: Warren, Chem. News 74, 6 (1896); Hanson, U.S> pat. 2,028,390 (1936). Reviews of biology, pharmacology and toxicity of lithium ion: Schou, "Lithium in Psychiatry - A Review" in Psychopharmacology, A Review of Progress 1957-1967, D. H. Efron, Ed. (Public Health Service Publication No. 1836, (1968); Samuel, Gottesfeld, Endeavour 32, 122-128 (1973); Saran, Gaind, Clin. Toxicol. 6, 257-269 (1973); Schou, Ann. Rev. Pharmacol. Toxicol. 16, 231-243 (1976). Reviews: Hart, Beumel, "Lithium and its Compounds" in Comprehensive Inorganic Chemistry vol. 1, J. C. bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 331-367; R. Back, J. R. Wasson in Kirk-Othmer Encyclopedia of Chemical Technology vol. 14 (Wiley-Interscience, New York, 3rd ed., 1981) pp 448-476.

Silvery-white metal; body-centered cubic structure; becomes yellowish on exposure to moist air. mp 180.54°. bp 1336 ± 5°: Hartmann, Scheneider, Z. Anorg. Chem. 180, 275 (1929). d 0.534. heat capacity at constant pressure (25°): 5.892 cal/mole deg. See: Douglass et al., J. Am. Chem. Soc. 77, 2144 (1955). E° (aqueous) Li/Li+ 3.045 V. Reacts with H2O forming the hydroxide and H2 Attacked rapidly by dil HCl and H2SO4. slowly by concd H2SO4. Reacts vigorously with HNO3. Sol in liq ammonia forming a blue soln. Does not react with oxygen at room temp; forms Li2O when heated to 100° or higher. Reacts with hydrogen at a read heat; combines directly with nitrogen, halogens and sulfur under proper conditions. Imparts a carmine-red color to a bunsen flame. Keep under mineral oil or other liquid free from oxygen or water.

USE: In manuf of alloys, especially lithium-hardened bearing metals; as a "getter" in vacuum tubes. In making catalysts for the polyolefin plastics industry, in fuels for aircraft and missiles. Lithium salts are used in porcelain enamels, in air-conditionning, and for makin multi-purpose greases. Human Toxicity: Li ion may injure kidneys, especially if sodium intake is limited.