Simulate radioactive decay chains for alpha, beta, and gamma emitters.
Radioactive decay is a spontaneous nuclear process in which an unstable nucleus emits particles or radiation to reach a more stable configuration. Nuclear chemistry appears in AP Chemistry Unit 1, USNCO examinations, and as an IChO theoretical topic with connections to both chemistry and physics.
Alpha (α) decay emits a helium-4 nucleus (²He, 2 protons + 2 neutrons), decreasing the atomic number by 2 and mass number by 4. Alpha particles have the highest ionizing power but the shortest range — stopped by a sheet of paper. Alpha decay is common among heavy nuclei above bismuth (Z > 83).
Beta-minus (β⁻) decay converts a neutron to a proton, emitting an electron and an antineutrino. The mass number is unchanged; the atomic number increases by 1. Beta-plus (β⁺) decay converts a proton to a neutron, emitting a positron and a neutrino; atomic number decreases by 1. Electron capture is an alternative to β⁺ where the nucleus absorbs an inner-shell electron.
Gamma (γ) radiation is high-energy electromagnetic radiation emitted when a nucleus transitions between energy states. It has no charge and no mass, so neither the atomic number nor mass number changes. Gamma rays have the greatest penetrating power, requiring lead or thick concrete for shielding.
Radioactive decay follows first-order kinetics: N = N₀e^(−λt), where λ is the decay constant. The half-life t₁/₂ = ln2/λ = 0.693/λ is independent of initial quantity — a defining property of first-order processes. Carbon-14 dating uses this: ¹⁴C (t₁/₂ = 5,730 years) decays at a known rate, allowing the age of organic materials to be determined from the remaining ¹⁴C/¹²C ratio.
This nuclear decay simulator plots activity versus time for any nuclide, simulates decay chains, and calculates remaining activity after any number of half-lives — covering everything from AP Chemistry homework to USNCO preparation.