RADIUM (RA)

last update 01 oct 08

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

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   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
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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.