Home > Strontium
5 Isotopes
The alkali earth metal strontium has four stable, naturally occurring isotopes:
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 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.
Sixteen unstable isotopes are known to exist. Of greatest importance is Sr-90 with a half-life of 29 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.
6 Precautions
In its pure form strontium is extremely reactive with air and spontaneously combusts. It is therefore considered to be a fire hazard .
The human body absorbs strontium as if it were calcium. The stable forms of strontium do not pose a significant health threat, but the radioactive strontium-90 can lead to various bone disorders and diseases, including bone cancer . The strontium unit is used in measuring radioactivity from absorbed strontium-90.
7 References
8 External links
Chemical elements
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