nuclear reaction

Reaction involving the nuclei of atoms. Atomic nuclei can undergo changes either as a result of radioactive decay, as in the decay of radium to radon (with the emission of an alpha particle):

22688Ra → 22286Rn + 42He

or as a result of particle bombardment in a machine or device, as in the production of cobalt-60 by the bombardment of cobalt-59 with neutrons:

5927Co + 10n → 6027Co + γ.

Nuclear fission and nuclear fusion are examples of nuclear reactions. The enormous amounts of energy released arise from the mass–energy relation put forward by Einstein, stating that E = mc2 (where E is energy, m is mass, and c is the velocity of light).

In nuclear reactions the sum of the masses of all the products is less than the sum of the masses of the reacting particles. This lost mass is converted to energy according to Einstein's equation.