Ionisation – occurs when an atom loses electrons.
Thermionic Emission - is the giving off of electrons from the surface of a hot metal.
Photoelectric Effect – is the emission of electrons from a metal due to light of a suitable frequency falling upon it.
Photon – is a discrete amount (packet) of electromagnetic radiation.
Electron Volt – is the energy lost or gained by an electron when it moves through a potential difference of one volt.
Atomic Number – of an atom tells us the number of protons present in the atom.
Mass Number – of an atom tells us the number of protons plus neutrons present in the atom.
Isotopes – are atoms which have the same Atomic Number but different Mass Numbers.
Radioactivity – is the disintegration of unstable nuclei with the emission of alpha, beta or gamma radiation.
Half-life – of an element is the time taken for half of the nuclei in a sample to decay.
Law of Radioactive Decay – states that the number of disintegrations per second is proportional to the number of nuclei present.
Mass Number – of any element expressed in grams contains Avogadro’s Number of atoms.
Nuclear Fission – is the breaking up of a large nucleus into two smaller nuclei with the release of energy.
Nuclear Fusion – is the joining together of two small nuclei to form one larger nucleus with the release of energy and neutrons.