Atomic Number 36     Atomic Mass 83.80     State gas    

Color colorless     Melting Point -156.6°C     Boiling Point -152.30°C

Natural Isotopes Kr-78 0.35%   Kr-80 2.25%    Kr-82 11.6%
                           Kr-83 11.5%   Kr-84 57.0%   Kr-86 17.3%

Abbreviated Electron Configuration [Ar] 3d¹⁰ 4s² 4p⁶

Discovered by Sir William Ramsay and Morris W. Travers in 1898.