Periodic Table of Elements




Potassium was discovered by Sir Humphrey Davy in 1807 in England. Potassium was the first metal that was isolated by electrolysis. Potassium in nature occurs only in ionic salts.

Name: Potassium
Symbol: K
Atomic number: 19
Atomic weight: 39.098
State: solid
Group, period, block: 1, 4, s
Color: silvery gray
Classification: alkali metal
Electron configuration: 4s1

Physical properties

Density: 0.862 g/cm-3
Melting point: 336.53 K, 63.38 C, 146.08 F
Boiling point: 1032 K, 759 C, 1398 F

Atomic properties

Oxidation states: 1
Electronegativity: 0.82 (Pauling scale)
Ionization energies: 1st: 418.8 kJmol-1
Covalent radius: 20312 pm
Van der Waals radius: 275 pm
  • K
  • Electron Configuration


There are three naturally occurring isotopes of potassium exist, 39K, 40K and 41K.
40K is radioactive isotope.