CHEM.14.A

Alpha particles (helium nuclei) are relatively large and have a 2+ charge.   They generally travel only a few centimeters through the air and do not have to collide with other particles to transfer their energy. Energy transfer can occur through electromagnetic interactions which heavily ionize the matter the alpha particles interact with. Alpha radiation will not penetrate a barrier, such as the skin or a piece of paper. External exposure to alpha radiation is relatively harmless but it can be damaging if consumed. Americium-241 produces alpha radiation and is used in smoke detectors.

Beta particles are highly energetic electrons that are ejected when a proton or neutron is converted and have a 1- charge. Beta particles can travel multiple meters through the air and can penetrate the skin, transferring their energy to internal structures. Shielding such as plexiglass is often used when handling beta radioactive materials to prevent harm. Strontium-90 produces beta radiation and is used in cancer treatments.

Gamma rays are high-energy photons that can ionize matter. They can travel thousands of meters before transferring their energy. Gamma radiation is heavily penetrating and emitters must be shielded by very dense materials like lead. Carbon-14 and Uranium produce beta radiation. The decay of Carbon-14 to Carbon-12 can be used to carbon date organic materials, and the natural decay of Uranium is used in nuclear reactors to produce electricity.