RADIUM (RA)

last update 01 sep 10

* Radium is a member of the alkaline earth metals family:

alkaline earth metals in the periodic table

   ____________________________________________________________________

   RADIUM / Ra / 88

   A soft, silvery, lustrous, very radioactive metal.  Over two dozen
   isotopes are known, all unstable, the longest-lived being 
   Ra<226/88>, with a half-life of 1,620 years.  It is found in nature
   since it is part of a decay series, as are the other two naturally
   occurring isotopes, Ra<223/88> -- with a half-life of 11.5 days
   -- and Ra<224/88> -- with a half-life of 3.7 days.

     atomic weight:       226.0254
     abundance:           86th
     density:             5 g/cc
     melting point:       700 C      
     boiling point:       1,140 C
     valence:             2
   ____________________________________________________________________

Radium has traditionally been used as the active component of luminous paint for watches and dials, though in an era of electronic watches and displays that usage is of declining importance.