Radioisotope decay reactions

Some radioisotopes, such as uranium-238, are found in nature even though they are not stable. Other radioisotopes do not exist in nature but can be synthesized in nuclear reactions. To understand this distinction, we must realize that different nuclei undergo radioactive decay at different rates. Many radioisotopes decay essentially completely in a matter of seconds, so we do not find them in nature. Uranium-238, on the other hand, decays very slowly. Therefore, despite its instability, we can still observe what remains from its formation in the early history of the universe. 

Radiocarbon dating (43) has probably gained the widest general recognition (see Radioisotopes). Developed in the late 1940s, it depends on the formation of the radioactive isotope and its decay, with a half-life of 5730 yr. After forms in the upper stratosphere through nuclear reactions of... 

Unstable niobium isotopes that are produced in nuclear reactors or similar fission reactions have typical radiation hazards (see Radioisotopes). The metastable Nb, = 14 yr, decays by 0.03 MeV gamma emission to stable Nb Nb, = 35 d, a fission product of decays to stable Mo by... 

The process of radioactive decay (also known as radioactivity) involves the ejection from a nucleus of one or more nuclear particles and ionizing radiation. Nuclear fission is a reaction in which the nucleus splits into smaller nuclei, with the simultaneous release of energy. Most radioisotopes undergo radioactive decay processes and are converted into different smaller atoms. 

Radioactive decay is a first-order process, and the half-lives of the radioisotopes are well documented (see the chapter on Nuclear Chemistry for a discussion of half-lives with respect to nuclear reactions). 

Seventeen radioisotopes have been synthesized in nuclear reactions. Among them Kr-85 and Kr-87 have the longest half-lives of 10 and 6 % years, respectively, both undergoing beta decay. 

Americium-241, a radioisotope used in smoke detectors, decays by a series of 12 reactions involving sequential loss of a, a, (3, a, a, (3, a, a, a, (3, a, and f3 particles. Identify each intermediate nuclide and the final stable product nucleus. 

Some nuclei are unstable and emit particles and electromagnetic radiation. These emissions from the nucleus are known as radioactivity the unstable isotopes are known as radioisotopes and the nuclear reactions that spontaneously alter them are known as radioactive decay. Particles commonly involved in nuclear reactions are listed in the following table ... 

Because radioactive isotopes seem to decay at very constant rates, they can be used as clocks. One of the first radioactive dating techniques involved the use of the radioisotope carbon-14. Carbon-14 is produced in the upper atmosphere when neutrons (produced by cosmic rays from space) collide with nitrogen-14 molecules in the reaction shown below ... 

The tremendous release of energy from nuclear reactions makes possible a unique family of applications for long-lived radioisotopes that are important to health, science, and industry. Whereas fission and fusion occur almost instantaneously, other radioactive decay processes occur in times ranging from a few minutes to thousands of years. The general areas of application may be grouped into irradiation, thermal energy generation, and tracer applications.57... 

The radiation emitted from decay of single atoms can be easily measured. Thus, small amounts of radioisotopes can be incorporated into systems to study, for example, chemical reactions and the flow of fluids through complex systems such as organs of the human body. They also can be used in more mundane applications such as locating leaks in buried piping. Many organic compounds tagged with... 

A radioactive isotope (radioisotope) is an unstable isotope of an element that decays into a more stable isotope of the same element. They are of great use in medicine as tracers (to help monitor particular atoms in chemical and biological reactions) for the purpose of diagnosis (such as imaging) and treatment. Iodine (-131 and -123) and Technetium-99 are used for their short half-lives. 

As you may recall, isotopes are atoms of the same element that have different numbers of neutrons. Isotopes of atoms with unstable nuclei are called radioisotopes. These unstable nuclei emit radiation to attain more stable atomic configurations in a process called radioactive decay. During radioactive decay, unstable atoms lose energy by emitting one of several types of radiation. The three most common types of radiation are alpha (a), beta ((3), and gamma (7). Table 25-2 summarizes some of their important properties. Later in this chapter you ll learn about other types of radiation that may be emitted in a nuclear reaction. 

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