The practical uses of radioactivity are enormous, but the deep study of nucleus brought some important concepts to light:
- Nuclear Binding Energy: A measure of nuclear stability, it is the energy required to break a nucleus into component protons and neutrons. The difference between the mass of an atom and the sum of the masses of protons, neutrons and electrons is called mass defect and the energy equivalent to their mass difference is the nuclear binding energy.
- Nuclear Fission: Process in which a heavy nucleus splits into two lighter nuclei of intermediate mass and one or more neutrons, which in turn cause splitting of other nuclei giving rise to a chain reaction. Nuclear plants manage the chain reaction to produce heat which creates steam, in turn used to generate electricity.
- Nuclear Fusion: Process where in two lighter nuclei combine to form a heavier one releasing an enormous amount of energy. Nuclear fusion reactions are used to power hydrogen or thermonuclear bombs.
In the above, it is to be noted that nuclear reactions are accompanied by energy changes a million times greater than those in a chemical reactions at atomic level.