PERIODIC ELEMENT
Ar (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 20 °C
Melting point : - 189 °C
Boiling point : - 185.7 °C
Vanderwaals radius : 0.192 nm
Ionic radius : unknown
Isotopes : 6
Electronic 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
 
Atomic Structure Uses (Lighting)