A metal that is silvery white and can be cut with a knife. Potassium is never found free in nature, but is obtained by electrolysis of the chloride or oxide.
Potassium is one the most reactive and electrospositive of metals.
Except for lithium it is the lightest known element. Potassium oxidises very rapidly in air and must be stored under argon or mineral oil. Potassium catches fire spontaneously on water. Potassium was dicovered by Sir Humphrey Davy in 1807. Potassium was discovered in England.