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actinium

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actinium


  3  definitions  found 
 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
 
  Actinium  \Ac*tin"i*um\,  n.  [Gr.  ?,  ?,  ray.]  (Chem.) 
  A  supposed  metal,  said  by  Phipson  to  be  contained  in 
  commercial  zinc;  --  so  called  because  certain  of  its 
  compounds  are  darkened  by  exposure  to  light. 
 
  From  WordNet  r  1.6  [wn]: 
 
  actinium 
  n  :  a  radioactive  element  of  the  actinide  series;  found  in 
  uranium  ores  [syn:  {Ac},  {atomic  number  89}] 
 
  From  Elements  database  20001107  [elements]: 
 
  actinium 
  Symbol:  Ac 
  Atomic  number:  89 
  Atomic  weight:  (227) 
  Silvery  radioactive  metallic  element,  belongs  to  group  3  of  the  periodic 
  table.  The  most  stable  isotope,  Ac-227,  has  a  half-life  of  217  years. 
  Ac-228  (half-life  of  6.13  hours)  also  occurs  in  nature.  There  are  22  other 
  artificial  isotopes,  all  radioactive  and  having  very  short  half-lives. 
  Chemistry  similar  to  lanthanum.  Used  as  a  source  of  alpha  particles. 
  Discovered  by  A.  Debierne  in  1899. 
 
 




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