Daily lessons coming soon
Beginning Monday 20 April, BBC Bitesize will publish daily online lessons for all ages. We'll also have a new dedicated TV channel full of learning content, podcasts on BBC Sounds and loads of educational video on iPlayer.
Three subatomic particles have different charges and masses. Radioactive particles decay and release alpha, beta and gamma radiation - natural and artificial sources of background radiation.
Isotopes are the atoms of an element with different numbers of neutrons. They have the same proton number, but different nucleon numbers.