The change in isotopes over time due to the emission of radioactive particles is known as

The change in isotopes over time is due to radioactive decay. It makes unstable radioisotope into stable isotope. It occurs due to emission of radiation, beta, alpha particle or electron, neutron, gamma radiation etc. The decay is constant and is used for measuring the half-life of a radioactive substance.

The appropriate response is radioactive decay. It is the unconstrained breakdown of a nuclear core bringing about the arrival of vitality and matter from the core. Keep in mind that a radioisotope has flimsy cores that don't have enough restricting vitality to hold the core together.