Ununtrium is a synthetic chemical element with the symbol Uut and atomic number 113. It was first synthesized in 2003 by a team of Russian and American scientists at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. The discovery was officially announced by the International Union of Pure and Applied Chemistry (IUPAC) on 28 August 2004.
A team led by Moscow State University professor Yuri Oganessian bombarded americium-243 with calcium-48 ions to produce four atoms of ununtrium. This synthesis used a new type of “superheavy” element, one that has an atomic mass greater than that of any other known element but is not radioactive enough to be considered unstable. Ununtrium is thus far only known to exist in very small quantities and for very short periods of time; its longest-lived isotope, ununtrium-286, has a half-life of just over two seconds.
Despite its brief existence, ununtrium is important for several reasons. First, it confirms the existence of an “island of stability” among the superheavy elements: earlier theoretical work had predicted that certain combinations of protons and neutrons would result in unusually long-lived nuclei. Second, ununtrium’s discovery helps scientists understand how elements are created in stellar nucleosynthesis—the process by which stars create heavy elements from lighter ones through nuclear fusion reactions. Finally, ununtrium may have applications in technology; because it can absorb large amounts of radiation without becoming dangerously radioactive itself, it may be useful as a shielding material or as a component of nuclear waste disposal systems.