What does alpha decay involve?

Alpha decay is a type of radioactive decay where an unstable atomic nucleus emits an alpha particle. An alpha particle is composed of two protons and two neutrons, which is essentially the same as a helium-4 nucleus. When a nucleus undergoes alpha decay, it loses this alpha particle, resulting in a new nucleus with a lower atomic number (two fewer protons) and a lower mass number (four fewer total nucleons). This process allows the original atom to transition to a more stable state.

The correct answer accurately captures the fundamental mechanism of alpha decay, emphasizing the loss of the alpha particle from the nucleus. This characteristic distinguishes alpha decay from other types of nuclear reactions, as it specifically involves the emission of these particles, leading to changes in both the identity and the stability of the original element.