Strontium is a chemical element with symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when it is exposed to air. Strontium has physical and chemical properties similar to those of its two neighbors calcium and barium. It occurs naturally in the minerals celestine, putnisite and strontianite.
Strontium has four effectively stable isotopes: 88Sr, 87Sr, 86Sr, and 84Sr, The three heaviest isotopes are theoretically stable; while 84Sr could, in theory, decay but has not been observed to do so. A total of 36 isotopes (plus 6 isomers) have been observed, ranging from 73Sr to 108Sr. One of these, 90Sr, has a half-life of 28.90 years. All other isotopes have half-lives under 3 months. One source predicts that 52 isotopes of Sr exist(1).
Both strontium and strontianite are named after Strontian, a village in Scotland near which the mineral was discovered in 1790 by Adair Crawford and William Cruickshank. The production of sugar from sugar beet was in the 19th century its largest application (see strontian process). At the peak of production of television cathode ray tubes, up to 75 percent of U.S. strontium consumption was used to make the faceplate glass. With the displacement of cathode ray tubes by other display methods in television sets, consumption of strontium has dramatically declined.
References
- "Decay Modes and a Limit of Existence of Nuclei"; H. Koura; 4th Int. Conf. on the Chemistry and Physics of Transactinide Elements; Sept. 2011.