Alpha decay
Alpha Decay
Alpha decay (pronounced: /ˈælfə dɪˈkeɪ/) is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms or 'decays' into an atom with a mass number that is reduced by four and an atomic number that is reduced by two.
Etymology
The term "alpha decay" was first used in the early 20th century. The word "alpha" is derived from the first letter of the Greek alphabet, α, which was used by early physicists including Ernest Rutherford to denote this particular type of radioactive decay. The term "decay" comes from the Latin 'decadere', meaning 'to fall away', which accurately describes the process of an atomic nucleus losing particles.
Process
In alpha decay, the unstable atom's nucleus ejects two protons and two neutrons, which is equivalent to ejecting a helium-4 nucleus. This is the alpha particle. The remaining atom has its atomic number reduced by two and its mass number reduced by four. This process is a quantum tunneling effect, as the alpha particles do not have enough energy to overcome the nuclear force that binds them to the nucleus.
Related Terms
- Radioactive decay: The process by which an unstable atomic nucleus loses energy by radiation.
- Alpha particle: A positively charged particle consisting of two protons and two neutrons.
- Quantum tunneling: A quantum mechanical phenomenon where a particle passes through a potential barrier that it classically cannot surmount.
- Nuclear force: The force that binds protons and neutrons together in the nucleus of an atom.
See Also
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