Radioactivity is the phenomenon in which we have spontaneous disintegration of the nucleus of one or more atoms with the emission of highly pentrating radiations. The phenomenon of radioactivity is confined entirely to heavier elements in the periodic table having atomic number ranging from 83 to 102. The phenomenon of radioactivity was accidently discovered by Becquerel.
The phenomenon is independent of the external agents like temperature, pressure, electric or magnetic field and the ‘physical’ or chemical state of the specimen. It was M. Curie who gave the name raioactive to all substances capable of emitting these rays. A simple experiment by Rutherford established that the radioactive radiations consists of three components known as α, particles β rays and γ rays. α particles are nothing but doubley ionized helium atoms, β rays are electrons moving with velocities compariable to the velocity of light and γ rays are electromagnetic radiations of very short wavelengths. We now discuss in some details the properties of each of these three components.
