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Chemists Report New Superheavy Elements




THOMAS TEGGE/LLNL
Two more boxes may need to be added to the periodic table. According to a report in the current issue of the journal Physical Review C scientists have observed the first ever evidence of superheavy elements 113 and 115.

Superheavy element hunting is not an easy task. The more protons and neutrons that are packed into a nucleus, the less stable an atom becomes. In order to manufacture elements heavier than uranium, which has 92 protons, scientists smash together smaller nuclei to form short-lived heavy nuclei. In the new work, a team of researchers from the Joint Institute for Nuclear Research in Dubna, Russia, and Lawrence Livermore National Laboratory blasted a target of americum-243 atoms (each having 95 protons) with a beam of calcium-48 atoms (which have 20 protons each). Out of billions of candidates, the investigators detected four atoms of element 115. After just 90 milliseconds, the novel nuclei each decayed into element 113, which had also never been seen before. Just over a second later, element 113 was gone, too, having decayed first into element 111 and then dubnium (element 105).

"This just opens up the horizon on the periodic table," remarks Ken Moody of Livermore. "It allows us to expand the fundamental principles of chemistry. From new chemistry comes new materials and new technology." For now, the two elements are known by monikers that refer to their atomic numbers, or the number of protons they contain: ununtrium (113) and ununpentium (115). The International Union of Pure and Applied Chemistry will rename them only after the discovery can be independently confirmed. (In 2002, the claimed discovery of element 118 was retracted after other collaborations failed to reproduce the results of the original 1999 experiment.)

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