Strontium
. Strontium, symbol Sr, chemically reactive, malleable, ductile metallic element. In group 2 (or IIa) of the periodic table , strontium is one of the alkaline earth metals . The atomic number of strontium is 38. Metallic strontium was first isolated by the British chemist Sir Humphry Davy in 1808; the oxide had been known as early as 1790. Strontium has a silvery color when freshly cut. It oxidizes readily upon exposure to air, and reacts with water to produce strontium hydroxide and hydrogen gas. Like the other alkaline earth metals, it is prepared by transforming the carbonate or sulfate into the chloride, which, upon electrolysis, yields the metal. Strontium melts at about 769° C (about 1416° F), boils at about 1384° C (about 2523° F), and has a specific gravity of 2.6. The atomic weight of strontium is 87.62. Strontium is never found in the elemental state, occurring chiefly as strontianite and celestite. Strontium ranks about 15th among the elements in natural abundance in the ea