Title: Holmium
CAS Registry Number: 7440-60-0
Literature References: Ho; at. wt 164.93032; at. no. 67; valence 3. A rare earth metal of the yttrium group; member of the lanthanide series. Naturally occurring isotope (mass number): 165; known artificial radioactive isotopes: 146-164; 166-170. Estimated abundance in earth's crust 1.15-1.4 ppm; occurs in rare earth minerals. Discovered by Soret in 1878 and independently by Cleve in 1879: Cleve,
Compt. Rend. 89, 478, 708 (1879). Purification of salts: Holmberg,
Z. Anorg. Chem. 71, 226 (1911). Separation from erbium: Driggs, Hopkins,
J. Am. Chem. Soc. 47, 363 (1925); from other rare earths: Spedding
et al., ibid. 69, 2812 (1947);
76, 2557 (1954). Absorption spectrum: Severin,
Z. Phys. 125, 455 (1949). Analysis by means of emission spectra: Smith, Wiggins,
Analyst 74, 95 (1949). Toxicity study: Haley
et al., Toxicol. Appl. Pharmacol. 8, 37 (1966). 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: Metal; hexagonal close-packed crystals. d 8.7947. mp 1474°. bp 2700°. Heat of fusion: 16.874 kJ/mol. Heat of sublimation (25°): 300.8 kJ/mol. Forms yellow-green salts.
Melting point: mp 1474°
Boiling point: bp 2700°
Density: d 8.7947
Derivative Type: Oxide
Synonyms: Holmia
Molecular Formula: Ho2O3
Molecular Weight: 377.86
Percent Composition: Ho 87.30%, O 12.70%
Properties: Yellow solid. Obtained by igniting the hydroxide, nitrate, sulfate, oxalate. Dissolves in acids with formation of a yellow salt.
Derivative Type: Chloride
Molecular Formula: HoCl3
Molecular Weight: 271.29
Percent Composition: Ho 60.79%, Cl 39.20%
Properties: Bright yellow, crystalline solid, mp 718°. Formed by heating the hydrated salt in a current of hydrogen chloride at 350°. LD50 in mice: 560 mg/kg i.p.; 7.2 g/kg orally (Haley).
Melting point: mp 718°
Toxicity data: LD50 in mice: 560 mg/kg i.p.; 7.2 g/kg orally (Haley)
Derivative Type: Bromide
Molecular Formula: HoBr3
Molecular Weight: 404.64
Percent Composition: Ho 40.76%, Br 59.24%
Properties: mp 914°.
Melting point: mp 914°
Derivative Type: Iodide
Molecular Formula: HoI3
Molecular Weight: 545.64
Percent Composition: Ho 30.23%, I 69.77%
Literature References: Obtained by passing hydrogen iodide over the anhydr chloride at 600°: Jantsch
et al., Z. Anorg. Chem. 207, 353 (1932).
Properties: Light-yellow solid. mp 1010 ±10°.
Melting point: mp 1010 ±10°
