Beta particles consist of high speed, high energy electrons, released when a neutron decays into a proton and an electron.

When an electron is released, an anti-neutrino will also be released. An anti-neutrino can be represented as \( ^0_0 \bar \nu\) .

They can be written as \( \beta ^- \) or \( ^0_{-1}e \).

After beta decay, the atomic number of the atom will increase by one and the mass number will not change. Beta decay can be expressed as an equation as follows:

\[^A_Z X \rightarrow ^{A}_{Z+1}Y + ^0_{-1}e + ^0_0 \bar \nu\]

For example, this equation shows the beta decay of carbon 14:

\[^{14}_7 C \rightarrow ^{14}_{7}N + ^0_{-1}e + ^0_0 \bar \nu \]

Beta particles are less ionising than alpha particles. They will travel a few metres in air and can be stopped by a 3mm sheet of aluminium.

Because beta particles have mass and charge, they will be deflected in both electric and magnetic fields.