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Old 06-15-2009, 11:53 PM   #11
J_rod7
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Exclamation Re: New, superheavy element to enter periodic table

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The "new" element 112 is most certainly not the first not last...:

Ununpentium is the temporary name of a synthetic superheavy element in the periodic table that has the temporary symbol Uup and has the atomic number 115.

Two isotopes are currently known, Uup-287 and Uup-288.

Element 115 also falls in the center of the theoretical island of stability. The most stable isotope of ununpentium is predicted to be Uup-299, containing the theorized "magic number" of 184 neutrons. The most neutron rich isotope to date is Uup-288, which contains 173 neutrons.

On February 2, 2004, synthesis of ununpentium was reported in Physical Review C by a team composed of Russian scientists at the Joint Institute for Nuclear Research in Dubna, and American scientists at the Lawrence Livermore National Laboratory. The team reported that they bombarded americium-243 with calcium-48 ions to produce four atoms of ununpentium. These atoms, they report, decayed by emission of alpha-particles to ununtrium in approximately 100 milliseconds.

The Dubna-Livermore collaboration has strengthened their claim for the discovery of ununpentium by conducting chemical experiments on the decay daughter 268Db. In experiments in June 2004 and December 2005, the Dubnium isotope was successfully identified by milking the Db fraction and measuring any SF activities. Both the half-life and decay mode were confirmed for the proposed 268Db which lends support to the assignment of Z=115 to the parent nuclei.

Theoretical calculation in a quantum tunneling model supports the experimental alpha decay half-lives.


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Last edited by J_rod7; 06-15-2009 at 11:57 PM. Reason: small changes
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