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What is radioactivity?

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Quick answer

Radioactivity is the process where unstable atomic nuclei lose energy by emitting radiation. As these atoms 'decay', they release particles or rays — a process used in everything from nuclear power to medical imaging and carbon dating. Unstable atomic nuclei release energy as radiation.

Key things to understand

  1. Unstable atomic nuclei release energy as radiation.
  2. This 'decay' can emit alpha, beta, or gamma radiation.
  3. Each radioactive element decays at a steady, known rate (half-life).
  4. It's used in power, medicine, and dating ancient objects.

People also ask

What causes radioactivity?
Unstable atomic nuclei shedding excess energy by emitting particles or rays as they decay.
What is a half-life?
The time it takes for half of a radioactive sample to decay — a fixed rate for each element.
Is all radioactivity dangerous?
High doses are harmful, but low levels are natural and everywhere; many uses are safe and beneficial.