Theory and Concepts7
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Laws of Radioactive Disintegration
The spontaneous breaking of a nucleus is known as Radioactive Disintegration. Rutherford and Soddy made an experimental study of the radioactive decay of various radioactive materials and gave the following laws:
(a). Radioactive decay is a random and spontaneous process. It is not influenced by external conditions such as temperature, pressure, electric field, etc. each decay is an independent event that occurs by a chance to take first.
(b). In any radioactive decay, either an α-particle or β-particle is emitted by the atom. Emission of both is impossible at a time. Moreover, an atom doesn’t emit more than one α-particle or more than one β-particle at a time. When a nuclide emits α-particle, its mass number is reduced by four and atomic number by two.
When a nuclide emits a β-particle, its mass number remains unchanged but the atomic number increases by one.
When a nuclide emits a gamma-ray, neither the mass number nor the atomic number changes.
The γ-radiation is emitted by the excited nucleus.
These laws are called the Displacement Laws.