Discovery of element 117: Super-heavy elements and the island of stability*

Element 117 (tennessine) joined the periodic table in November 2016. Two tennessine isotopes were synthesized by bombarding Bk-249 from Oak Ridge National Laboratory with Ca-48 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.