Strontium
Strontium, a lustrous, silver-white metallic chemical element. Many of strontium's properties resemble those of calcium; it is soft, malleable (capable of being hammered into shapes), and ductile (capable of being drawn into wire). It is also a good reducing agent, converting many metallic oxides and halides into their metals, and decomposes water even more vigorously than does calcium. When exposed to air, strontium quickly forms a yellowish oxide coating. Finely divided strontium particles ignite spontaneously in air.
Because of the brilliant red color strontium gives to flame, its principal use is in compounds for fireworks, flares, and tracer ammunition. Other uses are in ceramic glazes, glass for color television tubes, and special greases. Very little strontium is used in the pure metallic form.
Strontium was first detected as a separate element in 1790 by Adair Crawford of Scotland and was isolated in 1808 by the British chemist Sir Humphry Davy. The element occurs mainly in two ores, celestite and strontianite (named for Strontian, Scotland, from which the element's name is also derived). Most of the world's strontium supply comes from Mexico, Turkey, Iran, and Spain.
Strontium has four stable isotopes and several radioactive isotopes. One of these radioactive isotopes, strontium-90, is a major fallout hazard from nuclear explosions.
Symbol: Sr. Atomic number: 38. Atomic weight: 87.62. Specific gravity: 2.54. Melting point: 1,416 F. (769 C.). Boiling point: 2,523 F. (1,384 C.). The isotopes Sr-84, Sr-86, Sr-87, and Sr-88 are stable. Sr-90 has a half-life of about 28 years. Strontium belongs to Group IIA of the Periodic Table and has a valence of +2.