Ununpentium

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. It can be referred to as eka-bismuth.

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 "magic number" of 184 neutrons. The most neutron rich isotope to date is Uup-288, which contains only 173 neutrons.

Discovery
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 Researchin 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.


 * $$\,^{48}_{20}\mathrm{Ca} + \,^{243}_{95}\mathrm{Am} \to \,^{291}_{115}\mathrm{Uup} ^{*} \to \,^{288,287}\mathrm{Uup}$$

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 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 to the parent nuclei.

Proposed Names
Although it has been rumoured that the Dubna team have suggested the name Langevenium (Ln), in honour of French physicist F. Langeven, whose nuclear equations are used in nuclear theory, there is absolutely no evidence in the public domain of such a suggestion by the group. It should be noted that the JWP is currently assessing the claim of discovery of the Dubna group and should publish their decision shortly.

Chemical properties
For now element 115 has only been manufactured in the amount of a few atoms, so the chemistry of element 115 has yet to be researched, but chemistry and physics can tell us a lot about what to expect. Although element 115 is in the same group as bismuth, its chemistry will probably be strongly altered by relativistic effects. One important predicted difference from bismuth is the presence of a stable oxidation state of +1, and a Uup+ ion with a chemistry similar to Tl+. There has been some experimental data for other superheavy elements, such as element 112, which seems to confirm relativistic effects for superheavy elements.

In popular culture
Ununpentium has been theorized to be inside the island of stability. This probably explains why it was mentioned regularly in popular culture, especially in UFO conspiracy theories. The most popular account of element 115, from Bob Lazar, would require changes to a great many existing theories.