Ecology & Human Impact Module

Radiation Activity Instructions

Introduction

Of the types of radiation produced in nuclear decay reactions, the three most common are alpha particles (α), beta particles (β), and gamma rays (γ). All of them are considered to be forms of ionizing radiation, that is, when they strike atoms or molecules in their paths they cause electrons to be knocked away, forming ions or free radicals. While this is generally not much of a concern with inanimate materials, these highly reactive species can cause undesirable effects in living tissue.

Alpha particles are fast moving particles that contain two protons and two neutrons, which make them identical to helium nuclei, with a mass number of 4 and a charge of 2+. They are written using either the Greek letter α or the symbol for the helium nucleus, He-4.

Beta particles are high-energy electrons, with a mass number of 0 and a charge of 1–. They are identical to other electrons in the atom, but do not exist in the nucleus until a neutron decays into a proton and an electron. They are written with either the Greek letter β.

Gamma rays are high-energy photons (similar to X rays but higher energy). They are given the Greek letter γ.