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Nuclear Chemistry

Nuclear Chemistry 29
Chapter 18 Nuclear ChemistryChapter MapNuclides • Nuclide = a particular type of nucleus, characterized by a specific atomic number and nucleon number • Nucleon number or mass number = the number of nucleons (protons and neutrons) in the nucleus of a nuclide.Nuclide SymbolismNuclear Stability • Electrostatic force = the force that causes opposite electrical charges to attract each other. • Strong force = the force between nucleons (protons and neutrons). • Neutrons increase the attraction from the strong force without increasing electrostatic repulsion between nucleons.Band of StabilityAlpha EmissionBeta EmissionPositron EmissionElectron CaptureGamma EmissionNuclear Reactions • Nuclear reactions involve changes in the nucleus, whereas chemical reactions involve the loss, gain, and sharing of electrons. • Different isotopes of the same element may undergo very different nuclear reactions, even though an element’s isotopes all share the same chemical characteristics.Nuclear Reactions (cont.) • Unlike chemical reactions, the rates of nuclear reactions are unaffected by temperature, pressure, and the presence of other atoms to which the radioactive atom may be bonded. • Nuclear reactions, in general, give off much more energy than chemical reactionsNuclear EquationsGeneral Nuclear EquationsHalf-life = the time it takes for one-half of a sample to disappear.Radioactive Decay SeriesRadiation Effect on Body • Radioactive emissions ionize atoms and molecules. This also leads to free radicals (particles with unpaired electrons). + − ● H O → H O + e 2 2 + + ●● H O +H O → H O + OH 2 2 3 −− ● H O + e→ H + OH 2 • These reactive particles react with important substances in the body, leading to immediate damage and delayed problems, such as cancer.Uses for Radioactive Nuclides • Cancer radiation treatment • Computer imaging techniques • Radiocarbon dating • Smoke detectors • Food irradiation • Radioactive tracersNuclear Energy • Binding energy = the amount of energy released when a nucleus is formed. • Binding energy per nucleon generally increases from small atoms to atoms with a mass number around 56. Thus fusing small atoms to form medium-sized atoms (nuclear fusion) releases energy. • Binding energy per nucleon generally decreases from atoms with a mass number around 56 to larger atoms. Thus splitting large atoms to form medium- sized atoms (nuclear fission) also releases energy.Binding Energy per NucleonNuclear FissionChain ReactionNuclear ReactorNuclear Fusion Powers the Sun
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08-07-2017