Radioactive decay

Science

Definition

Radioactive decay is the spontaneous process by which an unstable atomic nucleus loses energy by emitting radiation in the form of alpha particles, beta particles, or gamma rays. The rate of decay is characterized by the half-life, the time it takes for half of a radioactive sample to decay.

Examples

  • Carbon-14 decaying with a half-life of 5,730 years, used in archaeological dating
  • Uranium-238 decaying through a series of steps into stable lead-206
  • Iodine-131 used in medical imaging decaying with an 8-day half-life
Key Fact

N(t) = N₀(½)^(t/t½), where t½ is the half-life

Related Terms

Half-life Nuclear physics Fission and fusion Subatomic particles

Study This Concept

Practice radioactive decay with free review games in these units:

Chemistry Unit 9: Nuclear Chemistry