Alpha particles are helium nuclei. A stream of alpha particles . Alpha rays rapidly dissipate their energy as they pass through materials, and are far less penetrating than beta particles and gamma rays . Compare with cation . An anion is a negatively charged ion.
Nonmetals typically form anions.
Compare with cathode . The electrode at which oxidation occurs in a cell. Anions migrate to the anode. Abbreviated as amu or u . Sometimes called the dalton , after John Dalton , architect of the first modern atomic theory .