Alpha Decay

Alpha decay is a type of radioactive decay by which an unstable isotope emits 2 protons and 2 neutrons from its nucleus (alpha particle). This alpha particle is basically a nucleus of Helium.

This process typically occurs for very heavy elements (high atomic number) and it causes the original nucleus to reduce its atomic mass by 4 and atomic number by 2. Any time that alpha decay occurs, the result is an alpha particle and a nucleus of an element with an atomic number 2 units lower than the original atom. For example, Polonium-210 (Z=84) undergoes alpha decay and is turned into Lead-206 (Z=82).