Radioactivity
Definition
The spontaneous breakup of unstable atomic nuclei, shooting out particles or energy: a nuclear process, not a chemical one.
Technical definition
Radioactivity is the spontaneous disintegration of unstable nuclei with emission of alpha particles, beta particles, or gamma rays. It follows first-order kinetics with a characteristic half-life and is unaffected by temperature, pressure, or chemical state.
Example
Carbon-14 decays by beta emission with a 5730-year half-life: the clock behind radiocarbon dating.
Common confusion
Radioactivity comes from the NUCLEUS, not the electrons. No chemical reaction can speed it up, slow it down, or stop it: only nuclear processes matter.