The Discovery of Element 117: Super-Heavy Elements and the “Island of Stability

Abstract

Element 117 (tennessine) joined the periodic table in November 2016. Two tennessine isotopes were synthesized by bombarding 249Bk from Oak Ridge National Laboratory with 48Ca ions at the Joint Institute of Nuclear Research, Russia, and 11 new heaviest isotopes of odd-Z elements were observed in subsequent decay chains. These isotopes exhibit increasing lifetimes as the closed nuclear shell at neutron number N = 184 is approached, providing evidence for the “island of stability” for super-heavy elements. This paper summarizes recent super-heavy element research with a focus on element 117, the role of actinide targets, and opportunities to synthesize elements 119 and 120.