Alpha decay is a type of radioactive decay in which an unstable atomic nucleus emits an alpha particle, consisting of two protons and two neutrons. This process reduces the atomic number of the original atom by two, transforming it into a different element. Alpha decay is common in heavy elements like Uranium and Radium, which seek stability by losing mass. The emitted alpha particle is relatively heavy and carries a positive charge, making it less penetrating than other forms of radiation. While alpha particles can be stopped by a sheet of paper, they can cause significant damage to biological tissues if ingested or inhaled, highlighting the importance of safety measures when handling radioactive materials.