Radioactivity is a nuclear phenomenon. It is the process of spontaneous emission of α (alpha particles) or β (beta particles) and γ (gamma particles ) radiations from the nucleus of atoms during their decay.
Uranium and radium are the two radioactive substances.
radioactivity is the act of emitting radiation spontaneously. This is done by an atomic nucleus that, for some reason, is unstable; it "wants" to give up some energy in order to shift to a more stable configuration.
