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Because of the way it reacts with air and water, strontium only exists in nature when combined to form minerals. Naturally occurring strontium is stable, but its synthetic isotope Sr-90 is only produced by nuclear fallout. In groundwater strontium behaves chemically much like calcium. At intermediate to acidic pH Sr 2+ is the dominant strontium ...
The ratio 87 Sr/ 86 Sr is the parameter typically reported in geologic investigations; [4] ratios in minerals and rocks have values ranging from about 0.7 to greater than 4.0 (see rubidium–strontium dating). Because strontium has an electron configuration similar to that of calcium, it readily substitutes for calcium in minerals.
Naturally occurring strontium is nonradioactive and nontoxic at levels normally found in the environment, but 90 Sr is a radiation hazard. [4] 90 Sr undergoes β − decay with a half-life of 28.79 years and a decay energy of 0.546 MeV distributed to an electron, an antineutrino, and the yttrium isotope 90 Y, which in turn undergoes β − decay with a half-life of 64 hours and a decay energy ...
Strontium-86 and strontium-87 are both stable isotopes of strontium, but strontium-87 is radiogenic, coming from the decay of rubidium-87. The ratio of these two isotopes depends on the concentration of rubidium-87 initially and the age of the sample, assuming that the background concentration of strontium-87 is known.
The nuclides found naturally comprise not only the 286 primordials, but also include about 52 more short-lived isotopes (defined by a half-life less than 100 million years, too short to have survived from the formation of the Earth) that are daughters of primordial isotopes (such as radium from uranium); or else are made by energetic natural ...
No chemical analysis was possible at the time, but helium was later found to be a noble gas. Before them, in 1784, the English chemist and physicist Henry Cavendish had discovered that air contains a small proportion of a substance less reactive than nitrogen. [10]
None of the alkaline earth metals are found in their elemental state. Common magnesium-containing minerals are carnallite, magnesite, and dolomite. Common calcium-containing minerals are chalk, limestone, gypsum, and anhydrite. [2] Strontium is the 15th most abundant element in the Earth's crust. The principal minerals are celestite and ...
Strontium nitride, Sr 3 N 2, is produced by burning strontium metal in air (resulting in a mixture with strontium oxide) or in nitrogen. Like other metal nitrides , it reacts with water to give strontium hydroxide and ammonia: