Element: Argon

Atomic number

18

Atomic mass

39.948 g.mol -1

Electronegativity according to Pauling

unknown

Density

1.78.10 -3 g.cm -3 at 0 °C

Melting point

-189 °C

Boiling point

-185.7 °C

Vanderwaals radius

0.192 nm

Ionic radius

unknown

Isotopes

6

Electronis shell

[Ne] 3s23p6

Energy of first ionisation

1520 kJ.mol -1

Energy of second ionisation 2665.8 kJ.mol -1
Energy of third ionisation 3931 kJ.mol -1

Discovered by

Sir Ramsay in 1894