Describe carbon dating
A half-life usually describes the decay of discrete entities, such as radioactive atoms.In that case, it does not work to use the definition that states "half-life is the time required for exactly half of the entities to decay".For example, if there is just one radioactive atom, and its half-life is one second, there will not be "half of an atom" left after one second.
We can write them as or, because they're the same as an electron, . Beta particles have a medium penetrating power - they are stopped by a sheet of aluminium or plastics such as perspex. Gamma rays do not directly ionise other atoms, although they may cause atoms to emit other particles which will then cause ionisation.
Beta particles ionise atoms that they pass, but not as strongly as alpha particles do. We don't find pure gamma sources - gamma rays are emitted alongside alpha or beta particles.