What is the term for the decay process where a radioactive atom loses energy and mass?

The process referred to in this question is known as radioactive decay. This term describes the natural transformation of unstable atomic nuclei as they emit energy and mass in the form of radiation. During radioactive decay, an unstable isotope undergoes a series of changes that ultimately lead to a more stable form, often resulting in the release of particles such as alpha particles, beta particles, or gamma rays.

Radioactive decay is a fundamental concept in nuclear physics and is crucial for understanding how radioactive materials behave, including their half-lives and the types of radiation they emit. This process is a key part of various applications, including medical treatments, energy generation, and understanding the age of materials through radiometric dating.

In contrast, nuclear fission refers specifically to the splitting of a heavy nucleus into smaller nuclei, which is used in nuclear power and weapons. Ionization involves the removal of electrons from atoms, leading to the formation of charged particles, and radiation emission broadly describes any release of energy in the form of particles or electromagnetic waves. While ionization and radiation emission can be related to decay processes, they do not specifically capture the entirety of what happens during radioactive decay, making it the most precise term for this phenomenon.