Title: Plutonium
CAS Registry Number: 7440-07-5
Literature References: Pu; at. no. 94; valences 3, 4, 5, 6, 7. No stable nuclides, known isotopes (mass numbers): 232-246. Longest-lived known isotopes: 242Pu (T½ 3.76 ´ 105 years, a-emitter, rel. at. mass 242.0587), 244 (T½ 8.26 ´ 107 years, a-emitter, rel. at. mass 244.0642). Commercially useful isotopes: 238Pu (T½ 87.74 years; a-emitter, rel. at. mass 238.0496); 239Pu (T½ 2.41 ´ 104 years; a-emitter, rel. at. mass 239.0522). Occurrence in the earth's crust: 10-22%. Discovery of isotope 238Pu: G. T. Seaborg et al., Phys. Rev. 69, 366, 367 (1946); of isotope 239Pu: J. W. Kennedy et al., ibid. 70, 555 (1946). Isoln of 239Pu from pitchblende: G. T. Seaborg, M. L. Perlman, J. Am. Chem. Soc. 70, 1571 (1948). Prepn of metal: B. B. Cunningham, L. B. Werner, ibid. 71, 1521 (1949). Chemical properties: Seaborg, Wahl, ibid. 1128; Harvey et al., J. Chem. Soc. 1947, 1010. Reviews: J. M. Cleveland, The Chemistry of Plutonium (Gordon & Breach, New York, 1970) 653 pp; C. Keller, The Chemistry of the Transuranium Elements (Verlag Chemie, Weinheim, English Ed., 1971) pp 333-484; Comprehensive Inorganic Chemistry vol. 5, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) passim; Handb. Exp. Pharmakol. 36, 307-688 (1973); F. Weigel in Kirk-Othmer Encyclopedia of Chemical Technology vol. 18 (Wiley-Interscience, New York, 3rd ed., 1982) pp 278-301; Plutonium Chemistry, W. T. Carnall, G. R. Choppin, Eds. (Am. Chem. Soc., Washington, D.C., 1983) 484 pp; F. Weigel et al. in The Chemistry of the Actinide Elements vol. 1, J. J. Katz et al., Eds. (Chapman and Hall, New York, 1986) pp 499-886. Review of toxicology: W. J. Bair, R. C. Thompson, Science 183, 715-722 (1974); and health effects: Toxicological Profile for Plutonium (PB91-180406, 1990) 206 pp.
Properties: Silvery-white metal. Highly reactive. Oxidizes readily in dry air and oxygen, rate increases in presence of moisture. Six allotropic forms: simple monoclinic a-form, d21 19.86, transforms to b-form at 122 ±4°; body-centered monoclinic b-form, d190 17.70, transforms to g-form at 207 ±5°; face-centered orthorhombic g-form, d235 17.14, transforms to d-form at 315 ±3°; face-centered cubic d-form, d320 15.92, transforms to d¢-form at 457 ±2°; body-centered tetragonal d¢-form, d405 16.00, transforms to e-form at 479 ±4°; body-centered cubic e-form, d490 16.51, transforms to liquid at mp 640 ±2°.
Melting point: mp 640 ±2°
Density: d21 19.86; d190 17.70; d235 17.14; d320 15.92; d405 16.00; d490 16.51
Derivative Type: Trivalent plutonium
Properties: Weak reducing agent. Stable in soln in absence of air. Slowly oxidized to the tetravalent plutonium by atmospheric oxygen, by permanganate in acid soln in the cold; oxidized to the hexavalent form by permanganate at 60°. Trivalent salts are blue; form complexes very readily; form a series of double sulfates. Crystal structure of the complex and double salts: Zachariasen, J. Am. Chem. Soc. 70, 2147 (1948).
Derivative Type: Tetravalent plutonium
Properties: Reduced in aq soln to the trivalent form by sulfur dioxide, hydroxylamine hydrochloride, hydrazine hydrochloride, the uranous ion, the iodide ion; by shaking with mercury in chloride soln; electrolytically at a platinum cathode. Tetravalent salts are pink or greenish; form complexes very readily.
Derivative Type: Hexavalent plutonium
Properties: Obtained by the action of strong oxidizing agents (ceric salts, dichromates, permanganates, or hot bromate soln contg nitric acid) on the tri- or tetravalent form. Reduced to tri- or tetravalent plutonium by sulfur dioxide or ferrocyanide.
CAUTION: Radiation hazard; handling requires special equipment and shielding facilities. Animal studies have indicated that inhaled 239Pu as particulate matter may remain in the lungs, or move to the bones, liver or other body organs, and over a period of time may give rise to neoplasms due to its a-emitting radioactive decay. See Katz et al., loc. cit. vol. 2, p. 1128, 1182-1188. Max permissible concn of 238Pu in air: 7 ´ 10-13 mCurie/cc; of 239Pu in air: 6 ´ 10-13 mCurie/cc: Natl. Bur. Stand. Handb. 69, 87 (1959). See also Handb. Exp. Pharmakol. loc. cit.
Use: 238Pu as heat source; as radioisotope thermoelectric generator; in radionuclide batteries for pacemakers. 239Pu as fuel in atomic weapons and nuclear power reactors. |