19: Nuclear Chemistry

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Most chemists pay little attention to the nucleus of an atom except to consider the number of protons it contains because that determines an element’s identity. However, in nuclear chemistry, the composition of the nucleus and the changes that occur there are very important. Applications of nuclear chemistry may be more widespread than you realize. Many people are aware of nuclear power plants and nuclear bombs, but nuclear chemistry also has applications ranging from smoke detectors to medicine, from the sterilization of food to the analysis of ancient artifacts. In this chapter, we will examine some of the basic concepts of nuclear chemistry and some of the nuclear reactions that are important in our everyday lives.

19.01: Radioactivity
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.
19.02: The History and Basics of Fission
Nuclei that are larger than iron-56 may undergo nuclear reactions in which they break up into two or more smaller nuclei. This releases large amounts of energy in the form of heat, light, and gamma radiation.
19.03: Instruments for Radiation Detection
Such measurements are complicated by two factors. First, we cannot see, hear, smell, taste, or touch radiation, and so special instruments are required to measure it. Second, different types of radiation are more dangerous than others, and corrections must be made for the relative harm done by α particles as opposed to, say, γ rays.
19.04: Half-Life
Natural radioactive processes are characterized by a half-life, the time it takes for half of the material to decay radioactively. The amount of material left over after a certain number of half-lives can be easily calculated.
19.5: Uses of Radioactive Isotopes
Radioactivity has several practical applications, including tracers, medical applications, dating once-living objects, and preservation of food.
19.06: Nuclear Energy
Nuclear energy comes from tiny mass changes in nuclei as radioactive processes occur. In fission, large nuclei break apart and release energy; in fusion, small nuclei merge together and release energy.
19.07: Fission and Fusion
Nuclear fission is a process in which a very heavy nucleus splits into smaller nuclei of intermediate mass. Because the smaller nuclei are more stable, the fission process releases tremendous amounts of energy. Nuclear fusion is a process in which light-mass nuclei combine to form a heavier and more stable nucleus. Fusion produces even more energy than fission. In the sun and other stars, four hydrogen nuclei combine at extremely high temperatures & pressures to produce a helium nucleus.
19.08: Nuclear Reactors
A nuclear reactor is a device in which nuclear reactions are generated, and the chain reaction is controlled to release large amount of steady heat, thereby producing energy.
19.09: Breeder Reactors
The production of plutonium can be carried out in a breeder reactor which not only produces energy like other reactors but is designed to allow some of the fast neutrons to bombard the U235, producing plutonium at the same time. More fuel is then produced than is consumed. Breeder reactors present additional safety hazards
19.10: Nuclear Fusion
19.11: Biological Effects of Radiation
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 because it can ionize molecules or break chemical bonds, which damages the molecule and causes malfunctions in cell processes. Types of radiation differ in their ability to penetrate material and damage tissue, with alpha particles the least penetrating but potentially most damaging and gamma rays are most penetrating.

Thumbnail: Part of carbon–nitrogen–oxygen (CNO) reaction chain diagram, made just to be illustrative for nuclear reactions in general. Image used with permission (CC BY-SA 3.0; Michalsmid).