Radium takes its name from the Latin word radius or ray. All isotopes of radium are radioactive and many exhibit luminescence, reacting readily with oxygen and water. The metal was discovered and isolated in 1911 by Marie Curie.
When first discovered, compounds of the metal were used on watch dials for self-luminescence and in early cancer therapy. It has been all but replaced now by safer alternatives.
Stephen R. Marsden (ChemTopics)