Atomic Element Z = 18 • Noble Gas
Argon (Ar) — Atomic Data, Electron Shells & Reactions
Argon (symbol Ar, atomic number 18) has a standard atomic weight of 39.948 u and ground-state configuration [Ne] 3s2 3p6.
Atomic Number (Z)
18
IUPAC Symbol
Ar
Standard Atomic Weight
39.948 g/mol
Period / Group / Block
3 / 18 / p-block
Condensed Electron Config
[Ne] 3s2 3p6
Full Subshell Config
1s2 2s2 2p6 3s2 3p6
Principal Shell Occupancy
[2, 8, 8]
Pauling Electronegativity
—
First Ionization Energy
1521 kJ/mol
Covalent Radius
106 pm
Melting Point
83.81 K (-189.34 °C)
Boiling Point
87.3 K (-185.85 °C)
Density
0.001784 g/cm³
Oxidation States
0
Ar (Z=18) — Valence shell highlighted in vermilion