Nuclear Chemistry and Radioactivity Flashcards

Grade 12 · Science · Flashcards

Key nuclear chemistry vocabulary for Grade 12 Science.

Flashcards

Radioactive decay: Spontaneous emission of particles or energy from an unstable nucleus to achieve stability.
Alpha (α) particle: A ⁴₂He nucleus (2 protons + 2 neutrons); low penetrating power, stopped by paper.
Beta-minus (β⁻) particle: High-energy electron emitted when a neutron converts to a proton; medium penetrating power.
Gamma (γ) ray: High-energy electromagnetic radiation; no change in Z or A; highest penetrating power.
Half-life (t₁/₂): Time for 50% of a radioactive sample to decay; constant for each isotope regardless of conditions.
Nuclear fission: Splitting of a heavy nucleus (e.g., ²³⁵U) by a neutron; releases energy + more neutrons → chain reaction.
Nuclear fusion: Merging of light nuclei (e.g., ²H + ³H → ⁴He); releases more energy per nucleon than fission; powers stars.
Mass defect: The difference between the mass of separated nucleons and the actual nuclear mass; converted to binding energy.
Binding energy: Energy released when nucleons combine to form a nucleus; equivalent to mass defect via E = mc².
Radiocarbon dating: Uses ¹⁴C decay (t₁/₂ = 5,730 yr) to estimate age of organic materials up to ~50,000 years old.
Chain reaction: Self-sustaining fission reaction where each fission event releases neutrons that trigger more fissions.
E = mc²: Mass-energy equivalence; a tiny mass converts to enormous energy because c = 3 × 10⁸ m/s.