Beta decay
The radioactive decay of an unstable nucleus by emitting a beta particle (electron: ⁰₋₁ e or ⁰₋₁ β) and an antineutrino. Beta-minus decay occurs when a neutron converts to a proton: n → p + e⁻ + ν̄. This increases atomic number by 1 (proton number rises) while mass number stays the same. Beta decay occurs in nuclei with too many neutrons relative to protons.
Formula
n → p + e⁻ + v̄
Real World
Carbon-14 undergoes beta-minus decay with a half-life of 5,730 years; archaeologists at the British Museum use this to radiocarbon-date ancient artefacts like the Lindow Man.
Exam Focus
Remember to include the antineutrino (v̄) in beta-minus equations — omitting it is a common mark-scheme error.
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