(So named (Dutch: potasch, "potash") in 1807 by Humphry Davy, who first isolated it from potash) A soft, silver-white, waxlike metallic chemical element, one of the alkali metals, that oxidizes rapidly when exposed to air. It occurs abudantly in nature in the form of its salts, which are used primarily in fertilizers. Potassium compounds are also used in making explosives, in making soaps and detergents, and in tanning leather and dyeing textiles. Potassium is essential to life, and non-toxic. One of its natural isotopes is radioactive, and although this radioactivity is mild, it may be one natural cause of genetic mutation in man.

Symbol: K
Atomic number: 19
Atomic weight: 39.0983
Density (at room temperature and pressure): 0.862 g/cc
Melting point: 63.38°C
Boiling point: 760°C
Main valence: +1
Ground state electron configuration: [Ar]4s1