Einsteinium

3 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Es \Es\ n.
     the chemical symbol for {einsteinium}, a transuranic element
     with atomic number 99. The atomic weight of the longest-lived
     isotope, with a half-life of 276 days, is 254. The first
     isotope discovered, having atomic weight 253 and a half-life
     of 20 days, was recognized in 1952 in the debris from a


     hydrogen bomb test. As much as 3 micrograms of einsteinium
     were produced by a complex process involving long irradiation
     of plutonium isotopes in nuclear reactors. Its chemical
     properties are those of a trivalent actinide element. --HCP61
  
     Syn: einsteinium, atomic number 99.
          [WordNet 1.5 +PJC]

From WordNet (r) 2.0 [wn]:

  einsteinium
       n : a radioactive transuranic element produced by bombarding
           plutonium with neutrons [syn: {Es}, {E}, {atomic number
           99}]

From Elements database 20001107 [elements]:

  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.