Potassium is a chemical element with symbol K (from Neo-Latin kalium) and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction and burning with a lilac flame.Symbol: K
Atomic number: 19
Electron configuration: [Ar] 4s1
Discovered: 1807
Atomic mass: 39.0983 ± 0.0001 u
Discoverer: Humphry Davy