History and Production
From Latin radius, meaning ray. It was discovered in 1898 by P. and M. Curie after processing tonnes of pitchblende. The metal itself was isolated in 1910 by M. Curie and A. Debierne by the electrolysis of radium chloride. Using mercury as the cahode radium forms an amalgam. Radium can be obtained from uranium minerals. About 10 tonnes of uranium ore must be processed to give 1 mg of radium. It is used to produce radon for cancer treatment.
It is also used to make luminous paints and neutron sources.
It is a brilliant white metal that quickly blackens on exposure to air. The metal and its salts exhibit luminescence.
It occurs alongside with uranium ores with a natural abundance of about 1 x 10-6 ppm.
Interatomic distance: -
Melting point: 700°C
Boiling point: 1140°C
Thermal conductivity/Wm-1K-1: 18.6 (27°C)
Density/kgm-3: 5000 est. (20°C)
Standard Thermodynamic Data (atomic gas)
Enthalpy of formation: 159 kJ/mol
Gibbs free energy of formation: 130 kJ/mol
Entropy: 176.5 J/mol K
Heat capacity: 20.8 J/mol K
Electronic configuration: [Rn] 7s2
Term symbol: 1S0
Electron affinity: - Electronegativity (Pauline): 0.9
Ionization energy (first, second, third): 509.289, 979.053, - kJ/mol