P7:Isotopes and Radioactivity

Isotopes

Atoms of the same element with different numbers of neutrons.

Radioactive decay

A random process where the nucleus gives out radiation to become stable.

Alpha particle

Consists of 2 protons and 2 neutrons; has a large range in air, is stopped by paper, and is very ionising.

Beta particle

An electron ejected from the nucleus at very high speed; formed in the nucleus when a neutron changes to a proton and an electron.

Gamma radiation

Electromagnetic radiation that can travel several metres in air and is weakly ionising; requires thick lead for shielding.

Half-life

The time it takes for the nuclei of the isotope in a sample to halve, also the time it takes for the count rate to fall to half.