Radioactive decay

Definition

Radioactive decay is the spontaneous transformation of an unstable atomic nucleus into a lighter nucleus, accompanied by emission of particles, radiation, or both. This process results in the release of energy.

5 Must Know Facts For Your Next Test

1. Radioactive decay can occur through alpha decay, beta decay, or gamma decay.
2. The rate of radioactive decay is measured in terms of half-life, which is the time it takes for half of a sample to decay.
3. Alpha particles are composed of two protons and two neutrons and have a +2 charge.
4. Beta decay involves the conversion of a neutron to a proton with the emission of an electron (beta-minus) or the conversion of a proton to a neutron with the emission of a positron (beta-plus).
5. Gamma rays are high-energy photons emitted from an excited nucleus as it returns to its ground state.

Review Questions

• What are the three main types of radioactive decay?
• How is the half-life related to radioactive decay?
• What particles are emitted during alpha and beta decays?

Related terms

Half-Life: The time required for half the atoms in a radioactive sample to undergo decay.

Alpha Decay:

A type of radioactive decay where an unstable nucleus emits an alpha particle (2 protons and 2 neutrons).

Gamma Ray: High-energy electromagnetic radiation emitted from a nucleus during radioactive decay.