Periodic Table of Elements




Oxygen was discovered by English chemist Joseph Priestley and Swedish chemist Carl Wilhelm Scheele in 1774 in England, Sweden.

Name: Oxygen
Symbol: O
Atomic number: 8
Atomic weight: 15.999
State: gas
Group, period, block: 16, 2, p
Color: colorless gas, pale blue liquid
Classification: Non-metallic
Electron configuration: 1s2 2s2 2p4

Physical properties

Density: 1495 kg m-3 or 1.429 g/L
Melting point: 54.8 [or -218.3 C (-360.9 F)] K
Boiling point: 90.2 [or -182.9 C (-297.2 F)] K

Atomic properties

Oxidation states: 2, 1, -1, -2
Electronegativity: 3.44 (Pauling scale)
Ionization energies: 1st: 1313.9 kJmol-1
Covalent radius: 662 pm
Van der Waals radius: 152 pm
  • O
  • Electron Configuration


There are three naturally occurring isotopes of oxygen exist, 16O, 17O, and 18O.