Astatine

Literature References: At; at. no. 85. Radioactive halogen; Group VIIA (17). One of the rarest elements in nature. Known oxidation states: -1, 0, +5; existence of +1, +3, +7 oxidation states uncertain. No stable nuclides; radioisotopes range in mass numbers from 194 to 223. Naturally occurring isotopes produced in the natural decay series of uranium: 215, 218, 219 (longest-lived natural isotope, T½ 56 sec). Most stable artificial isotopes: 209 (T½ 5.41 hr); 210 (T½ 8.1 hr, longest-lived isotope, rel. at. mass 209.9871); 211 (T½ 7.21 hr, rel. at. mass 210.9875). Prepn and characterization of 211At by cyclotron reaction 209Bi (a,2n): D. R. Corson et al., Phys. Rev. 58, 672 (1940); of other artificial isotopes by a-particle bombardment of bismuth: E. L. Kelley, E. Segre, Phys. Rev. 75, 999 (1949); Johnson et al., J. Chem. Phys. 17, 1, (1949); Neumann, J. Inorg. Nucl. Chem. 4, 349 (1957). Prepn, purifn and nuclear decay data for 211At: R. M. Lambrecht, S. Mirzadeh, Int. J. Appl. Radiat. Isot. 36, 443 (1985). Inorganic chemistry: G. W. M. Visser, E. L. Diemer, Radiochim. Acta 33, 145 (1983); idem, ibid. 47, 97 (1989). Toxicity studies of 211At: L. M. Cobb et al., Hum. Toxicol. 7, 529 (1988). Review: A. J. Downs, C. J. Adams, "Chlorine, Bromine, Iodine and Astatine" in Comprehensive Inorganic Chemistry vol. 2, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 1573-1594. Review of organic chemistry and potential biomedical applications: I. Brown, Adv. Inorg. Chem. 31, 43-88 (1987); K. Berei, L. Vasáros in The Chemistry of Halides, Pseudo-halides and Azides, S. Patai, Z. Rappaport, Eds. (John Wiley & Sons, Chichester, 1995) pp 787-819.