Which type of decay involves the ejection of a charged alpha particle from the nucleus?

Alpha decay is a process in which an unstable atomic nucleus ejects an alpha particle, which is made up of two protons and two neutrons. This type of decay typically occurs in very heavy elements, where the nucleus has too many protons and neutrons, leading to instability. The ejection of the alpha particle reduces the atomic number by two and the mass number by four, resulting in the formation of a different element that is more stable.

In contrast, beta decay involves the transformation of a neutron into a proton with the emission of a beta particle (an electron or positron), and gamma decay involves the release of gamma radiation without changing the number of protons or neutrons in the nucleus. Electron capture is another process where an electron is captured by a nucleus, leading to the transformation of a proton into a neutron. Each of these processes involves different mechanisms and particles, making alpha decay distinct in that it specifically refers to the ejection of a composite particle (the alpha particle) from the nucleus.