Argon

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

Argon (Ar) is chemical element 18, a noble gas in group 18, period 3 (PubChem).

Atomic number: 18
Symbol: Ar
Group: 18
Period: 3
Atomic mass: 39.9 u
Electron configuration: [Ne]3s2 3p6
Atomic radius (van der Waals): 188 pm
Ionization energy: 15.760 eV
Oxidation states: 0
Standard state: Gas
Melting point: 83.8 K
Boiling point: 87.3 K
Density: 0.0017837 g/cm³
Chemical group: Noble gas
Year discovered: 1894

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