Ununtrium

Ununtrium, or eka-thallium, is the temporary name of a synthetic element in the periodic table that has the temporary symbol Uut and has the atomic number 113. It comes from the alpha decay (release of a helium nucleus) of ununpentium. Following periodic trends it is expected to be a soft, silvery highly reactive metal, rather like sodium.

History
The first report of ununtrium was in August 2003 when it was identified as a decay product of ununpentium. These results were published on February 1, 2004, by a team composed of Russian scientists at Dubna (Joint Institute for Nuclear Research), and American scientists at the Lawrence Livermore National Laboratory.


 * $$\,^{48}_{20}\mathrm{Ca} + \,^{243}_{95}\mathrm{Am} \to \,^{288,287}\mathrm{Uup} \to \,^{284,283}\mathrm{Uut} \to\ $$

On July 23, 2004, a team of Japanese scientists at RIKEN detected a single atom of 278Uut using the cold fusion reaction between Bismuth-209 and zinc-70. They published their results on September 28, 2004.


 * $$\,^{70}_{30}\mathrm{Zn} + \,^{209}_{83}\mathrm{Bi} \to \,^{279}_{113}\mathrm{Uut} ^{*} \to \,^{278}_{113}\mathrm{Uut} + \,^{1}_{0}\mathrm{n}$$

The RIKEN team produced a further atom on April 2, 2005, although the decay data was different from the first chain, and may be due to the formation of a meta-stable isomer.

The Dubna-Livermore collaboration has strengthened their claim for the discovery of ununtrium by conducting chemical experiments on the decay daughter 268Db. In experiments in Jun 2004 and Dec 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 and Z=113 to the parent and daughter nuclei.

In June 2006, the Dubna-Livermore team synthesised ununtrium directly in the "warm" fusion reaction between neptunium-237 and calcium-48 nuclei. Two atoms of 282Uut were detected.


 * $$\,^{48}_{20}\mathrm{Ca} + \,^{237}_{93}\mathrm{Np} \to \,^{285}_{113}\mathrm{Uut} ^{*} \to \,^{282}_{113}\mathrm{Uut} + 3 \,^{1}_{0}\mathrm{n}$$

Proposed Names
Ununtrium is a temporary IUPAC systematic element name. Scientists from Japan have proposed the names Japonium (symbol Jp) or Rikenium (Rk) after RIKEN. It has been rumoured that the russian scientists would like to propose the name Becquerelium in honour of the discoverer of radioactivity, the French physicist Henri Becquerel. Although no evidence of this statement can be found, the russian team did previously write to the GSI team wishing to suggest Becquerelium as a name for element 110, which has subsequently been named darmstadtium. Therefore, the Dubna team have shown an interest in naming an element after Becquerel and may well do so if the JWP favours their claim of discovery.