Strontium

Isotopes

The alkali earth metal strontium has four stable, naturally occurring isotopes:

Related Topics:
Alkali earth metal - Isotope

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Sr-84 (0.56%), Sr-86 (9.86%), Sr-87 (7.0%) and Sr-88 (82.58%). Only Sr-87 is radiogenic; it is produced by decay from the radioactive alkali metal rubidium-87, which has a half-life of 48,800,000,000 years. Thus, there are two sources of Sr-87 in any material: that formed during primordial nucleo-synthesis along with Sr-84, Sr-86 and Sr-88, as well as that formed by radioactive decay of Rb-87. The ratio Sr-87/Sr-86 is the parameter typically reported in geologic investigations. Because strontium has an atomic radius similar to that of calcium, it readily substitutes for Ca in minerals. Sr-87/Sr-86 ratios in minerals and rocks have values ranging from about 0.7 to greater than 4.0.

Related Topics:
Radiogenic - Radioactive - Rubidium - Half-life - Geologic - Atomic radius - Calcium - Mineral - Rock

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Sixteen unstable isotopes are known to exist. Of greatest importance is Sr-90 with a half-life of 28.78 years. It is a by-product of nuclear fallout and presents a health problem since it substitutes for calcium in bone, preventing expulsion from the body. This isotope is one of the best long-lived high-energy beta emitters known, and is used in SNAP (Systems for Nuclear Auxiliary Power) devices. These devices hold promise for use in spacecraft, remote weather stations, navigational buoys, etc, where a lightweight, long-lived, nuclear-electric power source is required.

Related Topics:
Half-life - Nuclear fallout - Bone - Beta - Systems for Nuclear Auxiliary Power - Spacecraft

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