Alpha (α) decay
Definition
Alpha (α) decay is a type of radioactive decay where an unstable nucleus emits an alpha particle, consisting of 2 protons and 2 neutrons. This process reduces the atomic number by 2 and the mass number by 4.
5 Must Know Facts For Your Next Test
- Alpha particles are helium nuclei composed of 2 protons and 2 neutrons.
- In alpha decay, the parent nucleus loses an alpha particle, resulting in a daughter nucleus with an atomic number decreased by 2 and a mass number decreased by 4.
- Alpha particles have relatively low penetration power and can be stopped by a sheet of paper or human skin.
- Common examples of alpha emitters include radium-226 ($^{226}_{88}Ra$) decaying to radon-222 ($^{222}_{86}Rn$).
- Alpha decay is typically observed in heavy elements with atomic numbers greater than 82.
Review Questions
- What changes occur in the atomic number and mass number during alpha decay?
- Why do alpha particles have low penetration power compared to other types of radiation?
- Provide an example of an element that undergoes alpha decay.
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Related terms
Beta (β) Decay: A type of radioactive decay where a neutron is converted into a proton, emitting a beta particle (electron) and an antineutrino.
Gamma (γ) Decay: A type of radioactive decay where an excited nucleus releases energy in the form of gamma rays without changing its atomic or mass numbers.
Half-life: The time required for half the atoms in a sample of a radioactive substance to undergo decay.
