Radioactive Decay
The spontaneous process by which an unstable atomic nucleus loses energy by emitting ionizing radiation (particles or electromagnetic rays).
Governing formula
N(t) = N₀ e^(-λ t), A(t) = λ N(t)
SI unit
Bq (Bequerels = decays/s) or Ci (Curies)
In depth
Radioactive decay transforms a parent nuclide into a daughter nuclide to achieve greater nuclear binding stability. Principal decay modes include alpha emission, beta emission (electron or positron), electron capture, and gamma emission.
Examples in the real world
Radium-226 decaying spontaneously into Radon-222 by emitting an alpha particle.