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.
Isotopes
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 ¦Â + ¦Â + 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.
Occurrence
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)
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rhenium germanium zirconium cadmium hafnium
barium lithium beryllium strontium calcium
Tantalum gadolinium samarium yttrium ytterbium
Lutetium praseodymium holmium erbium thulium dysprosium
terbium europium lanthanum cerium neodymium scandium
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