A 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 would be part of a new category of elements, called superactinides.[1] These range from 120 to 153 (atomic number).
An example of a short half-life: the isotope, 260Sg, has a half-life of approximately y 4 ms (or 4 thousandths of a second);[2]