This lesson provides a basic introduction to nuclear chemistry and exponential functions. Students learn about the discovery and history of radioactive elements and the scientific and societal implications of these discoveries. They model natural radioactive decay as a background for understanding how radioactive elements are used in the controlled fission reactions used in nuclear reactors. Students also learn how to express half-lives of radioactive elements mathematically as exponential functions. A materials list, standards, safety notes, teacher background information, assessment, Internet resources, and references are provided. This book selection also includes the Table of Contents, About the Editors and Authors, Acknowledgments, Appendix, and Index.