Oxygen

Document v1 · published by Koskamo · updated 2026-10-04

Oxygen (O) is chemical element 8, a nonmetal in group 16, period 2 (PubChem).

Atomic number: 8
Symbol: O
Group: 16
Period: 2
Atomic mass: 15.999 u
Electron configuration: [He]2s2 2p4
Electronegativity (Pauling scale): 3.44
Atomic radius (van der Waals): 152 pm
Ionization energy: 13.618 eV
Electron affinity: 1.461 eV
Oxidation states: -2
Standard state: Gas
Melting point: 54.36 K
Boiling point: 90.2 K
Density: 0.001429 g/cm³
Chemical group: Nonmetal
Year discovered: 1774

Source and provenance

Original source: pubchem.ncbi.nlm.nih.gov
Published on Koskamo by: Koskamo
Citation version: Document v1
Reuse: PubChem periodic table data (NIH/NLM, pubchem.ncbi.nlm.nih.gov/ptable); group and period from Jefferson Lab via PubChem

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Version history

Published by Koskamo2026-10-04
Version 1