Bright Atoms, home
Periodic table / Other non-metals

8Oxygen

Oxygen is an other non-metal in group 16, period 2. At 25 °C it is a gas.

O
Shells: 2, 6. A simple picture: electrons do not move in circles.
Symbol
O
Atomic number
8 protons in the nucleus
Standard atomic weight
15.999 ± 0.001Commercial samples can have a changed isotope mix, because material has been processed or isotopes removed (for example lithium sold after its lithium-6 was taken out).
Electron configuration
[He] 2s2 2p4
Electrons in each shell
2, 6
Group, period, block
16, 2, p
Family
Other non-metals
State at 25 °C
gas
Electronegativity
3.44 (Pauling scale)
First ionisation energy
1313.9 kJ/mol (13.618055 eV)
Where these numbers come from

Atomic weight: IUPAC CIAAW, abridged standard atomic weights 2024. Electron configuration and ionisation energy: NIST Atomic Spectra Database. Family, state and electronegativity: PubChem. See Sources. Melting points, boiling points and densities are left out for now: published values differ between sources, and we will add them once each has been checked.