The focus of the first half of the chapter is designed to provide basic information about atoms and radiation to aid in later chapters. The first half covers the basics on atoms such as: an atom consists of Neutrons, Protons, and Electrons; the atomic number of an atom determines the amount of protons in one atom; and that protons are roughly 2000 times heavier than electrons (see atom). The concept of radiation is introduced through ionization which is the process of adding one or more electrons to, or removing one or more electrons from, atoms or molecules, thereby creating ions. From there certain particles can cause ionization. The ionizing particles are alpha particles (a type of ionizing radiation ejected by the nuclei of some unstable atoms that are large subatomic fragments consisting of two protons and two neutrons), beta particles (subatomic particles ejected from the nucleus of some radioactive atoms that are equivalent to electrons), gamma particles (electromagnetic energy photon) and energetic neutron radiation (energy released from an atom in the form of neutral particles called neutrons). The second half focuses on knowledge of radiation introduced into the environment and humans. Flower's and his team concluded in 1976 that low levels over a long exposure time can prevent a cell from dividing or further damaging genetic information.
