The Cutting Edge: Confirmation of Elements 113, 115, 117, and 118
On December 30, 2015, IUPAC officially verified the existence of the transactinide elements ununtrium, ununpentium, ununseptium, and ununoctium (Z = 113, 115, 117, 118). Confirmation of the discoveries of these elements completes period 7 of the periodic table; the most recent official confirmations were of flerovium and livermorium (Z = 114, 116) in 2012.
Credit for the discovery of ununtrium (Uut, Z = 113) has been given to the Superheavy Element Production Team at RIKEN (Japan), headed by Kosuke Morita (森田 浩介). This marks the first time that a Japanese team has been credited with the discovery of a new element. Their first results were published in 2004; an earlier report by a joint Russian-American team was not deemed conclusive enough to be considered a true “discovery”.
The discovery of elements ununpentium (Uup, Z = 115) and ununseptium (Uus, Z = 117) has been credited to a three-way collaboration between scientists at the Joint Institute for Nuclear Research (Dubna, Moscow Oblast, Russia), Lawrence Livermore National Laboratory (Livermore, California, USA), and Oak Ridge National Laboratory (Oak Ridge, Tennessee, USA). In addition, JINR and Livermore National Lab scientists are also credited with discovering ununoctium (Uuo, Z = 118). Synthesis of the element occurred at the Flerov Laboratory of Nuclear Reactions, led by Yuri Tsolakovich Oganessian (Юрий Цолакович Оганесян).
As per the official guidelines outlined by the IUPAC, the discoverers of these elements now have the right to choose a permanent name and two-letter chemical symbol for that element. RIKEN has considered a variety of names for element 113, including japonium (Jp) and rikenium (Rk); names for 115, 117, and 118 have yet to be suggested, although moscovium has been proposed in the past.
References:
(1) IUPAC Press Release
(2) Morita et al. J. Phys. Soc. Jpn. 2004, 73, 2593-2596.
(3) Oganessian et al. Phys. Rev. C 2004, 69, 021601.
(4) Oganessian et al. Phys. Rev. Lett. 2010, 104, 142502.
(5) Oganessian et al. Phys. Rev. C 2006, 74, 044602.
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