Strontium
Symbol: Sr
Atomic Number: 38
Atomic Mass: 87.62 amu (atomic mass units)
Melting Point: 769.0 C (1042.15 K, 1416.2 F)
Boiling Point: 1384.0 C (1657.15 K, 2523.2 F)
Number of Protons: 38
Number of Electrons: 38
Number of Neutrons: 50
Classification: Alkaline Earth Metal
Crystal Structure: Cubic
Density @ 293 K: 2.54 grams per cubic centimeter
Color: yellow-silver
While studying the barium carbonate containing mineral witherite in 1790 Irish chemist Adair Crawford obtained some unexpected results. He assumed the mineral was contaminated with another mineral which he name strontianite. In1808 the English chemist Sir Humphry Davy produced pure strontium using electrolysis of a mixture of strontium chloride and mercuric oxide. The element is named after the Scottish town of Strontian.
Strontium has never been found free in nature. The pure element is a soft sliver colored metal which is quickly oxidized to give a yellow color to its surface. It decomposes vigorously in water. Finely divided strontium will ignite spontaneously in air.
There are four naturally occurring stable isotopes of strontium. The most common of the stable isotopes is strontium-88 at 82.58%. In addition strontium as over thirty unstable isotopes with half-lives ranging from about 150 nanoseconds to 28.79 days.
The radioactive isotope strontium-90, which has a half life of 28.79 days, is found in the fall-out from nuclear explosions. It decays by beta decay to form ytterim-90. Strontium-90 presents a danger to life as it is absorbed in to the body where is can accumulate in the bones. The radiation has been found to affect the production of new red blood cells and so eventually lead to death of the affected individual.
Strontium is produced from the two mineral ores strontianite and celesite. Mineral ores containing strontium are treated with hydrochloric acid to produce strontium chloride. The strontium chloride is mixed with potassium chloride and then subjected to electrolysis to produce strontium and chloride.
Strontium has a number of industrial uses.
* It is used to refine zinc.
* Combined with iron it is used to make magnets.
* Is a constituent of the glass used to make television tubes.
* Strontium carbonate and strontium nitrate both burn with a bright red flame. These compounds are used for this ability in the production of signal flares and fireworks.
* Strontium titanate has a high refractive index and its ability to disperse light is greater than diamond. It has been used in jewelry manufacture although it is quite soft.
