Strontium is the chemical element with the symbol Sr and atomic number 38. An alkaline earth metal, It is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is exposed to air. It’s physical and chemical properties similar to those of its two vertical neighbors in the periodic table, calcium and barium. It occurs naturally mainly in The minerals celestine and strontianite, and is mostly mined from these.
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; it was identified as a new element the next year from its crimson-red flame test color. It was first isolated as a metal in 1808 by Humphry Davy using the then-newly discovered process of electrolysis. During the 19th century, strontium was mostly used in the production of sugar from sugar beet (see strontian process). At the peak of production of television cathode ray tubes, as much as 75 percent of strontium consumption in the United States was used for the faceplate glass. With the replacement of cathode ray tubes with other display methods, consumption of strontium has dramatically declined.
Characteristics and Properties of Strontium
- It is a soft metal like lead and, when freshly cut, has a silvery lustre. It rapidly reacts in air to take on a yellowish colour; therefore, it must be protected from oxygen for storage.
- It does not occur free in nature. Although it is widely distributed with calcium, there are only two principal ores of strontium alone, celestine (SrSO4) and strontianite (SrCO3).
- Its cosmic abundance is estimated as 18.9 atoms. It composes about 0.04 percent of Earth’s crust.
- The most important commercial source of strontium is celestine; more than two-thirds of the world’s supply comes from China, with Spain and Mexico supplying much of the remainder.
- Metallic strontium may be also obtained by reduction of the oxide with aluminum. The metal is malleable and ductile and a good conductor of electricity, but there are relatively few uses for elemental strontium. One of them is as an alloying agent for aluminum or magnesium in cast engine blocks and wheels; the strontium improves the machinability and creep resistance of the metal.