2. Nuclear

Half life

Time taken for the number of unstable nuclei to decay to half its original value

Activity

Rate of decay of nuclei in a radioactive sample

Decay constant

Probability of a single nucleus decaying per unit time

Atomic mass unit

1/12th the mass of an atom of C-12

Mass defect

The difference between an atoms mass and the sum of the masses of its protons and neutrons

Binding energy

Minimum energy required to separate a nucleus into constituent protons and neutrons

Fission

Splitting a large nucleus into smaller nuclei

Induced fission

Stable nucleus splits into smaller nuclei due to collision of slow moving neutron

Thermal neutrons

Slow moving neutrons with low kinetic energy which are in thermal equilibrium with moderator

Critical mass

Minimum amount of fuel to maintain a steady chain reaction

Fusion

Binding of 2 small nuclei to produce larger nuclei