What are the different types of radioactive decay processes?

The different types of radioactive decay processes are alpha decay, beta decay, gamma decay, and electron capture.

Alpha decay is a type of radioactive decay where an atomic nucleus emits an alpha particle, which consists of two protons and two neutrons. This process results in the original atom losing two protons and two neutrons, thus changing its atomic number and atomic mass. For example, uranium-238 undergoes alpha decay to form thorium-234.

Beta decay is another type of radioactive decay, which involves the transformation of a neutron into a proton, or a proton into a neutron. There are two types of beta decay: beta-minus decay and beta-plus decay. In beta-minus decay, a neutron in an atom's nucleus turns into a proton, an electron, and an electron antineutrino. The electron and the antineutrino are emitted from the nucleus. In beta-plus decay, a proton in the nucleus turns into a neutron, a positron, and a neutrino. The positron and the neutrino are emitted from the nucleus.

Gamma decay is a process where an excited nucleus releases excess energy in the form of a gamma photon. This process does not change the number of protons or neutrons in the nucleus, but it does lower the energy state of the nucleus. Gamma decay often follows other types of decay, as those processes can leave a nucleus in an excited state.

Electron capture is a process where a proton-rich nucleus absorbs an inner shell electron, transforming a nuclear proton into a neutron and emitting a neutrino. This process decreases the atomic number by one and leaves the atomic mass unchanged.

Each of these decay processes is a spontaneous event, meaning it occurs without any external influence. The rate at which these decays occur is characterised by the half-life of the radioactive substance, which is the time it takes for half of the substance to decay. Understanding these processes is crucial in fields such as nuclear physics, medicine, and environmental science.