Title: Terbium
CAS Registry Number: 7440-27-9
Literature References: Tb; at. wt 158.92535; at. no. 65; valences 3, 4. A lanthanide; belongs to the yttrium group of rare earth metals. Naturally occurring isotope (mass number): 159; known artificial radioactive isotopes: 144-158; 160-164. Abundance in earth's crust: 0.91-1.2 ppm; occurs in small quantities in monazite, cerite, gadolinite and other rare earth minerals. Discovered by Mosander, Skand. Naturför. Förh. 3, 387 (1842); Philos. Mag. [3] 23, 241 (1843). Sepn by fractional crystn and precipitation: Urbain, Compt. Rend. 139, 736 (1904); 141, 521 (1905); James, Bissel, J. Am. Chem. Soc. 36, 2060 (1914); by ion exchange: Spedding et al., ibid. 76, 2557 (1954). Prepn of metal by electrodeposition: eidem, J. Electrochem. Soc. 100, 442 (1953). Absorption spectrum: Urbain, loc. cit. Toxicity study: Haley, J. Pharm. Sci. 54, 663 (1965). Reviews of prepn, properties and compds: The Rare Earths, F. H. Spedding, A. H. Daane, Eds. (Krieger, Huntington, N.Y., 1971, reprint of 1961 ed.) 641 pp; Hulet, Bode, "Separation Chemistry of the Lanthanides and Transplutonium Actinides" in MTP Int. Rev. Sci.: Inorg. Chem., Ser. One vol. 7, K. W. Bagnall, Ed. (University Park Press, Baltimore, 1972) pp 1-45; Moeller, "The Lanthanides" in Comprehensive Inorganic Chemistry vol. 4, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 1-101; F. H. Spedding in Kirk-Othmer Encyclopedia of Chemical Technology vol. 19 (John Wiley & Sons, New York, 3rd ed., 1982) pp 833-854; Chemistry of the Elements, N. N. Greenwood, A. Earnshaw, Eds. (Pergamon Press, New York, 1984) pp 1423-1449. Brief review of properties: G. T. Seaborg, Radiochim. Acta 61, 115-122 (1993).
Properties: Silver-gray metal, easily oxidized in air. Hexagonal close-packed crystals at room temp; d 8.27 (Spedding, Daane, loc. cit. p. 183). mp 1356°. bp 3230°; also reported as bp 2480° (Moeller).
Melting point: mp 1356°
Boiling point: bp 3230°; bp 2480° (Moeller)
Density: d 8.27 (Spedding, Daane, loc. cit. p. 183)
Derivative Type: Oxide
Additional Names: Terbia
Molecular Formula: O3Tb2
Molecular Weight: 365.85
Percent Composition: O 13.12%, Tb 86.88%
Properties: A white solid.
Derivative Type: Oxide
Properties: Non-stoichiometric, approx composition, Tb4O7, for this formula Tb3+ and Tb4+ present in equal amounts. Dark brown or black solid; obtained by igniting the oxalate or the sulfate. Dissolves in hot concd acids with formation of salts; loses oxygen on heating; forms the oxide when heated in hydrogen.
Derivative Type: Nitrate
Molecular Formula: Tb(NO3)3
Molecular Weight: 344.94
Percent Composition: Tb 46.07%, N 12.18%, O 41.74%
Properties: Occurs as the hexahydrate, monoclinic crystals, mp 89.3°. See Urbain, cited by Mellor, A Comprehensive Treatise on Inorganic and Theoretical Chemistry 5, 695 (1929). LD50 in rats (mg/kg): 260 i.p.; >5000 orally (Haley).
Melting point: mp 89.3°
Toxicity data: LD50 in rats (mg/kg): 260 i.p.; >5000 orally (Haley)
Derivative Type: Chloride hexahydrate
Molecular Formula: TbCl3.6H2O
Molecular Weight: 373.38
Percent Composition: Tb 42.56%, Cl 28.49%, H 3.24%, O 25.71%
Properties: Prismatic deliquesc crystals. Very sol in water; forms supersaturated solns. Dehydrated on heating in hydrogen chloride at 180-200°. The anhydr chloride, crystals, d0 4.35; mp 588°; dissolves in water without hydrolysis. LD50 in mice (mg/kg): 550 i.p.; 5100 orally (Haley).
Melting point: mp 588°
Density: d0 4.35
Toxicity data: LD50 in mice (mg/kg): 550 i.p.; 5100 orally (Haley)

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