CAS No 7440-18-8 , ruthenium

Title: Ruthenium
CAS Registry Number: 7440-18-8
Literature References: Ru; at. wt 101.07; at. no. 44; valences 1-8; most common states 2, 3, 4. Group VIII (8). Naturally occurring isotopes: 96 (5.46%); 98 (1.87%); 99 (12.63%); 100 (12.53%); 101 (17.02%); 102 (31.6%); 104 (18.87%); artificial radioactive isotopes: 93-95; 97; 103; 105-108. Belongs to the platinum group of metals. Found in the minerals osmiridium, laurite, in platinum ores, in some copper-nickel ores. Discovered in 1828 by Osann; prepd in the pure state in 1845 by Klaus. Constitutes about 0.0004 ppm of the crust of the earth. Prepn from osmiridium: Fremy et al., cited by Mellor, A Comprehensive Treatise on Inorganic and Theoretical Chemistry 15, 499 (1936). Reviews of prepn, properties and chemistry of ruthenium and other platinum metals: Gilchrist, Chem. Rev. 32, 277-372 (1943); W. P. Griffith, The Chemistry of the Rarer Platinum Metals (John Wiley, New York, 1967) pp 1-41, 126-226; Livingstone in Comprehensive Inorganic Chemistry vol. 3, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 1163-1209.
Properties: Lustrous, hard metal; hexagonal, close-packed structure. d420 12.45. mp about 2450°; bp about 4150°. Sp heat (0°): 0.057 cal/g/°C. Does not react with acids, even aqua regia. Not oxidized by air in the cold; on heating combines readily with oxygen; the powdered metal forms the dioxide on igniting in air. Superficially attacked by concd alkaline hypochlorites. The powdered metal is attacked by chlorine above 200°; by bromine between 300-700°. Oxidized by fused alkali hydroxides. Forms alloys with platinum, palladium, cobalt, nickel, tungsten; forms definite compds with zinc and with tin.
Melting point: mp about 2450°
Boiling point: bp about 4150°
Density: d420 12.45
Use: As substitute for platinum in jewelry; for pen nibs; as hardener in electrical contact alloys, electrical filaments; in ceramic colors; catalyst in synthesis of long chain hydrocarbons.