Promethium
Structural Formula Vector Image
Title: Promethium
CAS Registry Number: 7440-12-2
Literature References: Pm; at. no. 61; valence 3. No stable nuclides, known radioactive isotopes (mass numbers): 132-155. Longest-lived known isotope: 145 (rel. at. mass 144.9127, T½ 17.7 years, a-emitter). Most available isotope: 147 (rel. at. mass 146.9151, T½ 2.6234 years, b-emitter). Abundance in the earth's crust reported as 4.5 ´ 10-20 ppm; present at low levels in uranium ores. Independent discovery in rare earth concentrate claimed by: J. A. Harris, B. S. Hopkins, J. Am. Chem. Soc. 48, 1585 (1926); J. A. Harris et al., ibid. 1594; and by: L. Rolla, L. Fernandez, Gazz. Chim. Ital. 56, 435 (1926). Synthetic prepn: H. B. Law et al., Phys. Rev. 59, 936 (1941). Positive identification from fission products of 235U by ion-exchange chromatography: J. A. Marinsky et al., J. Am. Chem. Soc. 69, 2781 (1947). Metal prepd by reduction of halides: Weigel, Angew. Chem. Int. Ed. 2, 326 (1963); E. J. Wheelwright, J. Phys. Chem. 73, 2867 (1969). Review of prepn, properties and compds: Boyd, J. Chem. Educ. 36, 3-14 (1959); Weigel, Fortschr. Chem. Forsch. 12, 539-621 (1969); 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. Review of chemistry, toxicology and industrial uses: Promethium Technology, E. J. Wheelwright, Ed. (American Nuclear Society, Hindsdale, IL, 1973) 395 pp. Brief review of properties: G. T. Seaborg, Radiochim. Acta 61, 115-122 (1993).
Properties: 147Pm, metallic solid; d 7.22. mp 1080° (Weigel); also reported as 1169° (Wheelwright). A number of salts have been prepared including the trihalides (PmX3), the sesquioxide (Pm2O3), the hydroxide [Pm(OH)3] and the nitrate [Pm(NO3)3.xH2O].
Melting point: mp 1080° (Weigel)
Density: d 7.22
Use: 147Pm as energy source for nuclear powered batteries, b-particle source for thickness gauges; in the prepn of self-luminous compds; as portable x-ray sources.

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