So far, up to the atomic number 118, only one element had yet to be produced — element 117, temporarily referred to as ‘ununseptium’. Yuri Oganessian and colleagues in Russia and the US have now announced doing just this, in a paper accepted on Monday in Physical Review Letters.
By bombarding the actinide berkelium (Bk-249 that has 97 protons and 152 neutrons) with calcium (Ca-48, with 20 protons and 28 neutrons), the team has produced 2 different isotopes of the elusive element 117: ‘117’-294, with a half-life of 78 milliseconds, ‘117’-293 with a half-life of 14 milliseconds, as ScienceNews explains.
Despite these very short half-lives, the authors mention that the decaying properties of element 117 support the existence of the famous ‘Island of Stability’, an area of the periodic table where superheavy elements – which normally decay extremely rapidly – are predicted to have extra stability, conferred by the arrangement of their nucleons in closed shells.
Only a couple of months after element 112 was officially named copernicium, which Neil had told us about here, it looks like the IUPAC will be kept busy pondering on a name and symbol for ‘ununseptium’.
(Associate Editor, Nature Chemistry)