U.S., Russian and Japanese scientists credited with official discoveries
The seventh row of the periodic table is officially full.
On December 30, the International Union of Pure and Applied Chemistry announced that a Russian-U.S. collaboration had attained sufficient evidence to claim the discovery of elements 115, 117 and 118. IUPAC awarded credit for the discovery of element 113 to scientists at RIKEN in Wako, Japan (SN Online: 9/27/12). Both groups synthesized the elements by slamming lighter nuclei into each other and tracking the decay of the radioactive superheavy elements that followed.