Alpha particle

An alpha particle is a type of subatomic particle that consists of two protons and two neutrons, which makes it identical to a helium nucleus. Alpha particles are emitted during the radioactive decay of heavy elements like uranium and radium. They are relatively heavy and positively charged, which means they can be stopped by a sheet of paper or even human skin. However, if ingested or inhaled, they can be harmful because they can damage living tissue. Alpha radiation is one of the three main types of radioactive decay, alongside beta particles and gamma rays.