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 with the capacity to use nuclear reactions that produce devastating explosions with horrible side effects on the earth as we know it, and on the surviving populations that 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. 17.2: The Discovery of Radioactivity Henri Becquerel, Marie Curie, and Pierre Curie shared the discovery of radioactivity. 17.3: Types of Radioactivity- Alpha, Beta, and Gamma Decay The major types of radioactivity include alpha particles, beta particles, and gamma rays. Fission is a type of radioactivity in which large nuclei spontaneously break apart into smaller nuclei. 17.4: Detecting Radioactivity Several different devices are used to detect and measure radiation, including Geiger counters, scintillation counters (scintillators), and radiation dosimeters. Probably the best-known radiation instrument, the Geiger counter (also called the Geiger-Müller counter) detects and measures radiation. Radiation causes the ionization of the gas in a Geiger-Müller tube. 17.5: Natural Radioactivity and Half-Life During natural radioactive decay, not all atoms of an element are instantaneously changed to atoms of another element. The decay process takes time and there is value in being able to express the rate at which a process occurs. A useful concept is half-life, which is the time required for half of the starting material to change or decay. Half-lives can be calculated from measurements on the change in mass of a nuclide and the time it takes to occur. 17.6: Radiocarbon Dating- Using Radioactivity to Measure the Age of Fossils and Other Artifacts Radiocarbon dating (usually referred to simply as carbon-14 dating) is a radiometric dating method. It uses the naturally occurring radioisotope carbon-14 to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years old. Carbon has two stable, nonradioactive isotopes: carbon-12 and carbon-13. There are also trace amounts of the unstable radioisotope carbon-14 on Earth. 17.7: The Discovery of Fission and the Atomic Bomb Nuclei that are larger than iron-56 may undergo nuclear reactions in which they break up into two or more smaller nuclei. These reactions are called fission reactions. When a neutron strikes a UU -235 nucleus and the nucleus captures a neutron, it undergoes fission, producing two lighter nuclei and three free neutrons. The production of the free neutrons makes it possible to have a self-sustaining fission process—a nuclear chain reaction. 17.8: Nuclear Power- Using Fission to Generate Electricity Fission reactions can be used in the production of electricity if we control the rate at which the fission occurs. The great majority of all electrical generating systems (whether coal burning power plants, hydroelectric plants, or nuclear power plants) all follow a reasonably simple design. 17.9: Nuclear Fusion- The Power of the Sun Fusion is a method for obtaining energy from nuclear reactions that lies in the fusing together of two light nuclei to form a heavier nucleus. 17.10: The Effects of Radiation on Life We are constantly exposed to radiation from naturally occurring and human-produced sources. This radiation can affect living organisms. Ionizing radiation is the most harmful type of radiation because it can ionize molecules or break chemical bonds, which damages the molecules and causes malfunctions in cell processes. Types of radiation differ in their ability to penetrate material and damage tissue. 17.11: Radioactivity in Medicine The field of nuclear medicine has expanded greatly in the last twenty years. A great deal of the expansion has come in the area of imaging. This section will focus on nuclear medicine involving the types of nuclear radiation introduced in this chapter. Contributions & Attributions Wikibooks