1.   All manmade elements heavier than uranium decay radioactively, and generally speaking, the heavier the element, the faster the decay.

2.   Plutonium, a manmade element produced from uranium, is tricky stuff.

3.   For decades, physicists have theorized the existence of super-heavy manmade elements with a much longer life.

4.   The new manmade elements are numbered according to how many protons are in their nuclei, not by their order of discovery.