Strontium is the chemical element with atomic number 38, symbol Sr.

Strontium, like calcium, is an alkaline earth. It is soft, malleable, gray-yellow. On contact with air, it forms a protective oxide film (passivation). It ignites and burns easily in the air and reacts with water.

Strontium was isolated by Sir Humphry Davy (England) in 1808 after its oxide was identified in the ore of a Scottish mine near Strontian, strontianite SrCO3 in 1790 by Thomas Charles Hope. This was based on the work of William Cruickshank and Adair Crawford (fr), the first to postulate the existence of an unknown element in Strontianite.

Main article: Isotopes of strontium.
Strontium has 35 known isotopes with a mass number between 73 and 107, and six nuclear isomers. Among them, four isotopes are stable and represent all of the natural strontium: 84Sr (0.56%), 86Sr (9.86%), 87Sr (7.0%) and 88Sr (82.58%). Although 84Sr is suspected of disintegrating by + + decay in 84Kr, the latter has so far never been observed and it remains considered stable. The standard atomic mass of strontium is 87.62 (1) u.

Strontium is found in minerals such as celestine SrSO4 and strontianite SrCO3.
The level of strontium present in the earth's crust is low (0.034%). Certain compounds (soluble) are present in sea water and certain sources (mineral waters)



rhenium    germanium    zirconium     cadmium     hafnium

      barium   lithium     beryllium     strontium     calcium

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