Nonmetal

Oxygen

Oxygen (O) has atomic number 8. PubChem classifies it as nonmetal.

Atomic number

8

Symbol

O

Atomic weight (source value)

15.999

Electron configuration

[He]2s2 2p4

Standard state

Gas

Electronegativity (Pauling)

3.44

Melting point (K)

54.36

Boiling point (K)

90.2

Density (g/cm³)

0.001429

Oxidation states

-2

Understanding this entry

Atomic number is the number of protons in the nucleus. Properties are reference values and may depend on conditions and measurement conventions. An atomic weight is not the mass of every isotope. For elements without a standard atomic weight, a source may report an isotope mass number. Blank source values are shown as unavailable rather than estimated.

Further reading and reference: NIH PubChem source dataset ↗. Values and educational summaries are not a substitute for specialised advice.