Title: Strontium
CAS Registry Number: 7440-24-6
Literature References: Sr; at. wt 87.62; at. no. 38; valence 2. Group IIA (2). Alkaline earth metal. Naturally occurring, stable isotopes: 88 (82.58%); 86 (9.86%); 87 (7.00%); 84 (0.56%). Known radioactive isotopes: 76-83, 85, 89, 90 (longest lived isotope, T½ 28.78 yr, b- decay), 91-102. Occurs in the minerals, celestine (SrSO4) and strontianite (SrCO3); found in small quantities associated with calcium or barium minerals. Abundance in earth's crust 384 ppm. First prepared in 1807 by Davy. Commercial production by thermal reduction of strontium oxide with aluminum. Prepn: Glascock, J. Am. Chem. Soc. 32, 1222 (1910); Matignon, Compt. Rend. 177, 1116 (1923); J. Chem. Soc. 126[ii], 44 (1924); Guntz et al., cited in Gmelins, Strontium (8th ed.) 29, 35 (1931). Reviews: Goodenough, Stenger, "Magnesium, Calcium, Strontium, Barium and Radium" in Comprehensive Inorganic Chemistry vol. 1, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 591-774; Chemistry of the Elements N. N. Greenwood, A. Earnshaw, Eds. (Pergamon Press, New York, 1984) pp 117-154; S. G. Hibbins in Kirk-Othmer Encyclopedia of Chemical Technology vol. 22 (Wiley-Interscience, New York, 4th ed., 1997) pp 947-955. Review of clinical use of 89Sr in pain palliation for metastatic bone cancer: G. B. Altman, C. A. Lee, Oncol. Nurs. Forum 32, 523-527 (1996). Review of toxicology and human exposure: Toxicological Profile for Strontium (PB2004-104400, 2004) 445 pp.
Properties: Silvery-white metal; face-centered cubic structure; rapidly becomes yellow on exposure to air and assumes an oxide film. The finely divided metal ignites spontaneously in air. d 2.6; mp 757 ±1°; bp 1366°. E0 (aq) Sr2+/Sr -2.89 V. Undergoes reactions characteristic of alkaline earth metals. Strong reducing agent. Keep under liquid containing no oxygen. The heated metal combines with hydrogen to form strontium hydride and with nitrogen to form strontium nitride. Metal and its salts emit characteristic brilliant red color in flame.
Melting point: mp 757 ±1°
Boiling point: bp 1366°
Density: d 2.6
NOTE: The problems of internal radiation hazards from radiostrontium are discussed by A. Engström et al., Bone and Radiostrontium (Wiley, New York, 1958).
Use: In fireworks, in red signal flares; on tracer bullets. Eutectic modifier in Al-Ag casting alloys to improve strength and ductility. Innoculant in ductile iron casting to control graphite formation.
Therap-Cat: 89Sr as antineoplastic (radiation source). |