Alongside beta particles, gamma rays, and neutrons, alpha particles are a type of radiation, also called alpha radiation. As with most forms of radiation, alpha particles are emitted from radioactive elements.
Alpha particles are relatively heavy and slow compared to their companions, so they pose little danger to humans unless ingested.
They are, however, frequently used in research — alpha particles were crucial in Ernest Rutherford’s discovery of the atomic nucleus, which was the foundation of his atomic model.
