In order to reach a more stable configuration, a nucleus will change from one form to another. The result of this change is radioactivity.

These spontaneous changes can occur in a variety of ways: a nucleus can decay by changing one of its neutrons into a proton with the simultaneous emission of an electron (beta decay), by emitting a helium nucleus (alpha decay), or by spontaneously fissioning (splitting) into two fragments. The average time for half of the original amount to decay is called the half-life. Each element’s half-life is a unique period