Strontium (Sr)

Strontium is softer than calcium and decomposes in water more vigorously. It does not absorb nitrogen below 380°C. It should be kept under kerosene to prevent oxidation. Freshly cut strontium has a silvery appearance, but rapidly turns a yellowish color with the formation of the oxide. The finely divided metal ignites spontaneously in air. Volatile strontium salts impart a beautiful crimson color to flames, and these salts are used in pyrotechnics and in the production of flares. Natural strontium is a mixture of four stable isotopes.

The name derives from Strontian, a town in Scotland. The mineral strontianite is found in mines in Strontian. The element was discovered in 1792 by the Scottish chemist and physician Thomas Charles Hope, who observed the brilliant red flame colour of strontium. It was first isolated by the English chemist Humphry Davy in 1808.

Strontium was discovered by Adair Crawford, an Irish chemist, in 1790 while studying the mineral witherite (BaCO3). When he mixed witherite with hydrochloric acid (HCl) he did not get the results he expected. He assumed that his sample of witherite was contaminated with an unknown mineral, a mineral he named strontianite (SrCO3). Strontium was first isolated by Sir Humphry Davy, an English chemist, in 1808 through the electrolysis of a mixture of strontium chloride (SrCl2) and mercuric oxide (HgO). Today, strontium is obtained from two of its most common ores, celestite (SrSO4) and strontianite (SrCO3), by treating them with hydrochloric acid, forming strontium chloride. The strontium chloride, usually mixed with potassium chloride (KCl), is then melted and electrolyzed, forming strontium and chlorine gas (Cl2).

Named after Strontian, a town in Scotland. Isolated by Davey by electrolysis in 1808, however, Adair Crawford recognized a new mineral (strontianite) as differing from other barium minerals in 1790.