Alpha radiation is the stream of alpha particles emitted when radioactive materials disintegrate. When radioactive material breaks down, there is a loss in the total mass of the products. According to the law of conservation of mass-energy there must be a corresponding energy release, which is the energy associated with the emission of the alpha particle. An alpha particle is a heavy nucleon, which is actually the nucleus of a helium atom. They are most active in unstable elements of high atomic mass.

The stability of an atom relies on the balance of two forces, the force of repulsion among protons and the strong nuclear force. The number of protons in the atom influences the electromagnetic force by which the positively charged proton repels other (positively charged) protons. The strong nuclear force that holds the nucleus together is enhanced by the number of neutrons in the...