 Seaborg published several books and journal articles during his tenure at the Atomic Energy Commission . He predicted the existence of elements beyond those on the periodic table , the transactinide series and the superactinide series of undiscovered synthetic elements . While most of these theoretical future elements have extremely short half @-@ lives and thus no expected practical applications , he also hypothesized the existence of stable super @-@ heavy isotopes of certain elements in an island of stability . Seaborg served as chairman of the Atomic Energy Commission until 1971 . 
