Chapter 25 Nuclear Chemistry Ch. 25.1 Nuclear Radiation

Radioactivity Radioactivity is the process by which materials give of rays and particles. The rays and particles given off are referred to as radiation. Nuclear reactions are different from chemical reactions…the nuclei change instead of the electrons. Radioisotopes—unstable isotopes that gain stability when the nuclei undergo changes.

Nuclear reactions are not affected by changes in temperature, pressure, or catalysts, and a given radioisotope’s nuclear reactions cannot be speeded up, slowed down, or stopped. Too many or too few neutrons relative to protons makes a nucleus unstable. An unstable nucleus released energy by emitting radiation during the process of radioactive decay.

Types of Radiation Alpha Radiation—consists of helium nuclei that have been emitted from a radioactive source (alpha particle—two protons and two neutrons). Alpha particles have a +2 charge and an mass number of 4. Alpha particles have low penetrating power, but alpha emitting radioisotopes are dangerous when ingested.

Beta Radiation A beta particle is created when a neutron in an atom breaks apart into a proton and an electron. The proton remains in the nucleus, and the fast-moving electron is released. A beta particle has a -1 charge, and a mass of 1/1837 amu. Higher penetrating power, but can be stopped by wood or metal foil.

Gamma Radiation Gamma rays are high energy photons (electromagnetic radiation) emitted by radioisotopes. Often accompany alpha or beta particles during radioactive decay. No mass or electrical charge. High penetrating power. Can be partially stopped by dense materials such as lead, steel, or concrete. Dangerous.