Electrons, protons and neutrons
Proton: positive charge about the same mass as a neutron
Electron: negative charge but smallest particle.
¹²₆C Atomic mass: number of protons and neutrons
Atomic number: number of protons
Alpha particles: Helium nuclei. Short range. Heavily ionising
Beta particles: Electrons. Long range. Less ionising.
Gamma rays: Photons. Extremely penetrating.
Alpha and Beta emissions change the atomic number of the original decaying element.
Decaying equations must balance. The sum of the atomic masses before and after the decay must be the same, as does the sum of the atomic numbers.
Radiation and half-life
You can detect ionising radiation by:
photographic film and The Geiger-Muller tube.
Nuclear power and weapons.
The rate of decay is measured in bacquerels (one decay per second)
The half-life of a radioactive isotope t½ is the time taken for half the original number of unstable nuclei to decay.
Medicine - Radioactive tracers / treat illnesses
Sterilisation - kills bacteria
Non-medical tracers - industrial process tracers
Radioactive dating - to find out how long a material has been dead
can kill living cells
can disrupt genetic material - cell mutation