Title: Scandium
CAS Registry Number: 7440-20-2
Literature References: Sc; at. wt 44.955912; at. no. 21; valence 3. Group IIIb (3). Rare earth metal. Naturally occurring isotope (mass number): 45; known artificial radioactive isotopes: 40-44, 46-51. Abundance in earth's crust: 5-25 ppm. Widely dispersed in nature. Occurs in the minerals thortveitite [(Sc,Y)2Si2O7] and in other rare earth minerals such as davidite, ytterbite, orthite and cerrite; frequently associated with tin or zirconium. Predicted and called "ekaboron" by Mendeleev. Discovered by Nilson:
Ber. 12, 551, 554 (1879);
13, 1430, 1439 (1880). Sepn from wolframite: Lukens,
J. Am. Chem. Soc. 35, 1470 (1913); on basis of solubility: Fischer, Bock,
Z. Anorg. Chem. 249, 146 (1942). Toxicity of the chloride: Haley
et al., J. Pharm. Sci. 51, 1043 (1962). Review of isolns including ion-exchange techniques: F. H. Spedding
et al., J. Electrochem. Soc. 105, 683-686 (1958). Review of prepn, properties and compds: R. C. Vickery,
The Chemistry of Yttrium and Scandium (Pergamon Press, New York, 1960) 123 pp;
idem, "Scandium, Yttrium and Lanthanum" in
Comprehensive Inorganic Chemistry vol. 3, J. C. Bailar, Jr.
et al., Eds. (Pergamon Press, Oxford, 1973) pp 329-353; T. Moeller, "The Lanthanides",
ibid. vol. 4, 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 1102-1110, 1423-1449.
Properties: Metal. Reported to be dimorphic. Crystalline forms: hexagonal close-packed a-form, d 2.9890; evidence of existence of face-centered cubic b-form, d 3.19, is inconclusive. mp 1541°. bp 2836°. Heat of fusion: 14.10 kJ/mol. Heat of sublimation (25°): 377.8 kJ/mol. E°(aq) Sc3+/Sc -2.08 V (calc). Salts are hydrolyzed in aq soln.
Melting point: mp 1541°
Boiling point: bp 2836°
Density: d 2.9890; d 3.19
Derivative Type: Oxide
Synonyms: Scandia
Molecular Formula: O3Sc2
Molecular Weight: 137.91
Percent Composition: O 34.80%, Sc 65.20%
Properties: Fine white powder, d 3.864. Obtained by igniting the metal or its compds. Readily sol in hot or concd acids.
Density: d 3.864
Derivative Type: Hydroxide
Molecular Formula: Sc(OH)3
Molecular Weight: 95.98
Percent Composition: Sc 46.84%, O 50.01%, H 3.15%
Properties: White gelatinous precipitate forming a hard, horny mass on exposure to air; obtained by the action of alkalies on solns of the salts; dissolves readily in dil acids.
Derivative Type: Chloride
Molecular Formula: ScCl3
Molecular Weight: 151.31
Percent Composition: Sc 29.71%, Cl 70.29%
Properties: White deliquescent solid. Prepd by the action of a mixture of sulfur chloride and chlorine on the heated oxide; mp 960°; crystallizes with 6 mols of water. Sol in water. Practically insol in alc. LD50 in mice: 755 mg/kg i.p.; 4 g/kg orally (Haley).
Melting point: mp 960°
Toxicity data: LD50 in mice: 755 mg/kg i.p.; 4 g/kg orally (Haley)
Derivative Type: Sulfate
Molecular Formula: Sc2(SO4)3
Molecular Weight: 378.10
Percent Composition: Sc 23.78%, S 25.44%, O 50.78%
Properties: Pentahydrate, d 2.519. Most sol of the sulfates of the rare earths (54.6 g/100 ml at 25°). Converted to the dihydrate on heating above 100°.
Density: d 2.519
Derivative Type: Nitrate
Molecular Formula: Sc(NO3)3
Molecular Weight: 230.97
Percent Composition: Sc 19.46%, N 18.19%, O 62.34%
Properties: Crystallizes as the tetrahydrate, prismatic deliquescent crystals, readily dissolves in water or alc.
