Here is the equation for the alpha decay of radon-219 into polonium. Beta decay involves the conversion of a down quark to an up quark. This changes a neutron into a proton plus an electron.

^{4}\textrm{He}\) and is also sometimes written as \(_{2}^{4}\alpha\). Alpha decay causes the mass number of the nucleus to decrease by four and the atomic number of the nucleus to decrease by two.