Radioactive decay which is also knows as nuclear decay is a process in which such atoms whose nucleus is unstable release mass by emitting radiation alpha particles, beta particles or gamma particles.
The type of radiation emitted depends upon the type of nuclei.Radioactive decay is a very random process for and is impossible to calculate the amount of time it will take to decay for a single atom. But for a collection of atoms, it can be calculated in terms of decay constant or half-life.
