Atomic Number: 19

Atomic Weight: 39.0983

Melting Point: 336.53 K (63.38°C or 146.08°F)

Boiling Point: 1032 K (759°C or 1398°F)

Density: 0.89 grams per cubic centimeter

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 4

Group Number: 1

Group Name: Alkali Metal

Although Potassium only has two stable isotopes (K-39 and K-41), the long-lived radioisotope K-40 is often also regarded as a stable isotope. Potassium isotopes, mainly K-40 and K-41, are used to study the impact of potassium on the growth of plants and of the human cardiovascular system.