Extended periodic table The next six elements on the periodic table should be the last main-group elements in their period. In elements 167 to 172, the 9p and 8p shells will be filled. Their energy eigenvalues are so close together that they behave as one combined "p" shell, similar to the non-relativistic 2p and 3p shells. Thus, the inert pair effect does not occur and the most common oxidation states of elements 167 to 170 should be +3, +4, +5, and +6 respectively. Element 171 (unseptunium) is expected to show some similarities to the halogens, showing various oxidation states ranging from −1 to
Extended periodic table be unbound and undergo proton emission. Cluster decay (heavy particle emission) has also been proposed as an alternative decay mode for some isotopes, posing yet another hurdle to identification of these elements. The following are the expected electron configurations of elements 118–173. Beyond element 122, no complete calculations are available and hence the data in this table must be taken as tentative. Extended periodic table An extended periodic table theorizes about chemical elements beyond those currently known and proven up through oganesson, which completes the seventh period (row) in the periodic table at atomic number ("Z") 118. If further elements