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 ein·stei·ni·um /aɪnˈstaɪniəm/
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 einsteinium
      n : a radioactive transuranic element produced by bombarding
          plutonium with neutrons [syn: Es, E, atomic number
          99]

 einsteinium
 Symbol: Es
 Atomic number: 99
 Atomic weight: (254)
 Appearance is unknown, however it is most probably metallic and silver
 or gray in color. Radioactive metallic transuranic element belonging to the
 actinoids. Es-254 has the longest half-life of the eleven known isotopes at
 270 days. First identified by Albert Ghiorso and associates in the debris of
 the 1952 hydrogen bomb explosion. In 1961 the first microgram quantities of
 Es-232 were separated. While einsteinium never exists naturally, if a
 sufficient amount was assembled, it would pose a radiation hazard.