Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle, which is a helium nucleus composed of two protons and two neutrons. The general equation representing alpha decay is:
$$^{A}{Z}X \rightarrow ^{A-4}{Z-2}Y + ^{4}_{2}\alpha$$
Here, the atomic mass number of the newly formed atom will be reduced by four and the atomic number will be reduced by two. Alpha decay occurs in massive nuclei that have a large proton to neutron ratio, and it minimizes the protons to neutrons ratio in the parent nucleus. The emitted alpha particle is relatively large and has a positive charge, which means it cant go very far through the air or get very deep into a solid. Alpha particles only affect surfaces, so alpha decay is rarely used in external medical radiation therapy.
Regarding the fate of electrons after alpha decay, they will lose energy by scattering on the fields of the atoms and molecules of the medium until they are captured. In alpha decay, the atom changes elements since the number of protons changes.
