In today’s society, the term radioactivity conjures up a variety of images. Nuclear power plants producing hydrocarbon-free energy, but with potentially deadly by-products that are difficult to store safely. Bombs that use nuclear reactions to produce devastating explosions with horrible side effects on the earth as we know it and on the surviving populations that would inhabit it. Medical technology that utilizes nuclear chemistry to peer inside living things to detect disease and the power to irradiate tissues to potentially cure these diseases. Fusion reactors that hold the promise of limitless energy with few toxic side products. Radioactivity has a colorful history and clearly presents a variety of social and scientific dilemmas. In this chapter we will introduce the basic concepts of radioactivity, nuclear equations and the processes involved in nuclear fission and nuclear fusion. 11.1: Radioactivity Certain elements spontaneously produced a variety of particles. The three basic classes of particles were identified as “alpha”, “beta”, and “gamma” particles. Alpha particles were positive, relatively massive and were showed to be identical to the nucleus of the helium atom. Beta particles had a very small mass and were of higher energy and they carried a negative charge. Gamma particles were much more energetic, appeared to be neutral and were comparable to a high-energy photon of light. 11.2: The Nuclear Equation To show radioactive decay in a chemical equation, you need to use atomic symbols. In the atomic symbol, the atomic number (the number of protons in the nucleus) appears as a subscript preceding the symbol for the element. The mass number appears as a superscript, also preceding the symbol. 11.3: Beta Particle Emission 11.4: Positron Emission A positron, also called an antielectron, is an exotic bit of matter, or more correctly, an example of antimatter. A positron is the antimatter equivalent of an electron. It has the mass of an electron, but it has a charge of +1. Positrons are formed when a proton sheds its positive charge and becomes a neutron. 11.5: Radioactive Half-Life 11.6: Nuclear Fission 11.7: Nuclear Fusion 11.S: Nuclear Chemistry (Summary)