Nuclear & Radiochemistry — 13 Terms Defined

Neutron Emission Nuclear & Radiochemistry MeV The direct ejection of a neutron from an extremely neutron-rich nucleus. ᴬ_Z X → ᴬ⁻¹_Z X + ¹₀n

Neutron-to-Proton Ratio Nuclear & Radiochemistry Dimensionless The ratio of neutrons to protons in a nucleus, the principal determinant of its stability and decay mode. N / Z

Nuclear Binding Energy Nuclear & Radiochemistry MeV The energy that would be required to separate a nucleus completely into its individual protons and neutrons. E = Δm c²

Nuclear Chain Reaction Nuclear & Radiochemistry Dimensionless A self-sustaining sequence of fissions in which neutrons released by one event trigger further events. k = neutrons produced / neutrons lost

Nuclear Chemistry Nuclear & Radiochemistry Dimensionless The study of changes that occur in atomic nuclei and of the properties of radioactive substances.

Nuclear Cross Section Nuclear & Radiochemistry barn A measure of the probability that a particular nuclear reaction will occur between a nucleus and an incident particle. σ, measured in barns

Nuclear Fission Nuclear & Radiochemistry MeV The splitting of a heavy nucleus into two lighter nuclei with the release of neutrons and a large amount of energy. ²³⁵U + n → fragments + 2–3n + energy

Nuclear Fuel Enrichment Nuclear & Radiochemistry Dimensionless The process of increasing the proportion of a fissile isotope above its natural abundance.

Nuclear Fusion Nuclear & Radiochemistry MeV The combining of light nuclei into a heavier one, releasing energy. ²H + ³H → ⁴He + n + 17.6 MeV

Nuclear Isomer Nuclear & Radiochemistry MeV A nucleus in a long-lived excited state that decays to its ground state by gamma emission. denoted with m, e.g. ⁹⁹ᵐTc

Nuclear Reactor Nuclear & Radiochemistry MW A device in which a controlled nuclear chain reaction generates heat for power or produces radioisotopes.

Nuclear Stability Nuclear & Radiochemistry Dimensionless The tendency of a nucleus to persist without undergoing radioactive decay.

Nuclide Nuclear & Radiochemistry Dimensionless A distinct species of atom characterised by a specific number of protons and neutrons in its nucleus. ᴬ_Z X