| A | B |
|---|
| nucleus | tiny dense centre of an atom |
| electron cloud | surrounds the nucleus |
| isotopes | atoms with different numbers of neutrons |
| number of electrons equals the | number of protons |
| elements | only one kind of atom |
| alpha particles | two neutrons and two protons |
| beta particles | fast moving electrons from the nucleus |
| gamma rays | electromagnetic radiation from the nucleus |
| radioactivity is emitted | randomly |
| Geiger Counter | detects all forms of ionising radiation |
| half-life | time for half the atoms in a substance to decay |
| after two half lives | one quarter of the original atoms are left |
| fission | an atoms spilts into two or more large chunks |
| control rods | neutron absorbers in a nuclear reactor |
| heat exchanger | exchanges heat from coolant to make steam |
