Strontium is the chemical element with the symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white yellowish metallic element that is highly chemically reactive.

While natural strontium (mostly the isotope strontium-88) is stable, synthetic strontium-90 is radioactive. In addition, it is one of the most dangerous components of nuclear fallout, as the body similarly absorbs strontium as calcium. Natural stable strontium, on the other hand, is not hazardous to health.

Alkali Metals and Alkaline Earth Metals

The alkali metals (group 1) have very similar properties: they are all shiny, soft, highly reactive metals at standard temperature and pressure and readily lose their outermost electron to form cations with charge +1. The alkaline earth metals are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure.

The alkali metals are a group (column) in the periodic table consisting of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).