Alpha decay

Definition

Alpha decay is a type of radioactive decay where an unstable nucleus emits an alpha particle, consisting of two protons and two neutrons. This process decreases the atomic number by 2 and the mass number by 4.

5 Must Know Facts For Your Next Test

1. An alpha particle is identical to a helium-4 nucleus.
2. Alpha decay reduces the parent atom's atomic number by 2 and its mass number by 4.
3. Alpha particles have low penetration power and can be stopped by a sheet of paper or human skin.
4. Common examples of alpha emitters include radium-226, uranium-238, and plutonium-239.
5. Alpha decay typically occurs in heavy nuclei where the electrostatic repulsion between protons is very strong.

Review Questions

• What particles are emitted during alpha decay?
• How does alpha decay affect the atomic number and mass number of the decaying nucleus?
• Why do heavy nuclei tend to undergo alpha decay?

Related terms

Beta Decay:

A type of radioactive decay in which a neutron turns into a proton or vice versa, emitting a beta particle (electron or positron) and an antineutrino or neutrino.

Gamma Decay:

A type of radioactive decay where an excited nucleus releases energy in the form of gamma rays without changing its atomic number or mass number.

$Q$ Value: $Q$ value refers to the amount of energy released during a nuclear reaction or radioactive decay, calculated as the difference in mass-energy between initial and final states.