18 Ar
Noble gas
Argon
Inert gas in welding and bulbs.
Properties of Argon
- Atomic number (Z)
- 18
- Symbol
- Ar
- Atomic mass
- 39.948 g/mol
- Category
- Noble gas
- Group
- 18
- Period
- 3
- Electron configuration
- [Ne] 3s² 3p⁶
- Electronegativity (Pauling)
- —
- Atomic radius
- 71 pm
- First ionization energy
- 1521 kJ/mol
- Melting point
- 83.8 K (-189.3 °C)
- Boiling point
- 87.3 K (-185.8 °C)
- Density
- 0.001784 g/cm³
- Phase at 25 °C
- Gas
- Discovered
- Discovered in 1894