Period 8 element
A period 8 element would be an element in the eighth period (row) of the periodic table.  No period 8 elements have been proven to exist. These elements are almost certainly too big to exist in nature, so they would be synthetic elements. They would probably decay very quickly, because of radioactivity, so they would have very short half-lives. However, some scientists believe that an island of stability may exist in this range, which would be more stable and have longer half-lives. Some of these elements would be part of a new category of elements, called superactinides. These range from 120 to 153 (atomic number).