18
Ar
39.948
Argon
Element 18 · 39.948 u · p-block
noble gas
The third most abundant gas in Earth's atmosphere. Used as an inert shielding gas in welding and lightbulbs.
Phase (STP)
Gas
Melting Point
-189.34 °C
Boiling Point
-185.85 °C
Density
0.0017837 g/cm³
Electronegativity
—
Atomic Radius
71 pm
Ionization Energy
1521 kJ/mol
Electron Affinity
0 kJ/mol
Discovered
1894 · Lord Rayleigh
Electron Configuration
[Ne] 3s2 3p6
Electron Orbitals
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