What is fission?

Fission is specifically defined as the process of splitting an atom's nucleus into smaller parts. This action releases a significant amount of energy and is the fundamental principle behind nuclear power generation and atomic bombs. When a heavy nucleus, such as that of uranium or plutonium, absorbs a neutron, it becomes unstable and splits apart, resulting in the formation of lighter elements and the release of energy, additional neutrons, and radiation. The released neutrons can then initiate further fission reactions in nearby heavy nuclei, leading to a chain reaction, which is a critical element in both controlled (nuclear reactors) and uncontrolled (nuclear weapons) fission processes.

The other options describe different processes: fusion involves the combination of lighter atomic nuclei to form a heavier nucleus, ionization refers to the removal of electrons from atoms, and non-ionizing radiation pertains to low-energy radiation that does not have sufficient energy to remove electrons. Understanding the distinction between these processes is crucial for comprehending the different mechanisms involved in nuclear physics and the practical applications of radioactive materials.