A-Level Physics Important Keywords.

Define Isotope

Atoms of the same element with different numbers of protons but the same number of electrons.

Define threshold frequency.

Minimum frequency of light that emits electrons

Define work function

Minimum energy needed to remove an electron from the surface of a metal

Define Ionisation energy

Minimum energy to remove an electron, in the ground state, from an atom

Define ground state.

The lowest energy level an atomic electron can be in.

Define excitation of an atom

Ttransition where an atomic electron gains an exact amount of energy and moves

to a higher energy level.

Define de-excitation.

Transition where an atomic electron loses exactly the energy difference between levels by emitting a photon and moving to a lower energy level.