Beyond element 172, there is the potential to fill the 6g, 7f, 8d, 10s, 10p 1/2, and perhaps 6h 11/2 shells. These electrons would be very loosely bound, potentially rendering extremely high oxidation states reachable, though the electrons would become more tightly bound as the ionic charge rises. Thus, there will probably be another very long transition series, like the superactinides.