25.3 Fission and Fusion > 1 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Chapter 25 Nuclear Chemistry 25.1 Nuclear Radiation

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<ul><li> Slide 1 </li> <li> 25.3 Fission and Fusion &gt; 1 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Chapter 25 Nuclear Chemistry 25.1 Nuclear Radiation 25.2 Nuclear Transformations 25.3 Fission and Fusion 25.4 Radiation in Your Life </li> <li> Slide 2 </li> <li> 25.3 Fission and Fusion &gt; 2 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Where does the suns energy come from? CHEMISTRY &amp; YOU The sun is about halfway through its life cycle. It has been producing energy for about 5 billion years and is expected to continue to produce energy for about 5 billion more. </li> <li> Slide 3 </li> <li> 25.3 Fission and Fusion &gt; 3 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Nuclear Fission What happens in a nuclear chain reaction? </li> <li> Slide 4 </li> <li> 25.3 Fission and Fusion &gt; 4 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Nuclear Fission When the nuclei of certain isotopes are bombarded with neutrons, the nuclei split into smaller fragments. This process is called fission. </li> <li> Slide 5 </li> <li> 25.3 Fission and Fusion &gt; 5 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Nuclear Fission The figure below shows how uranium-235 breaks into two smaller fragments of roughly the same size when struck by a slow-moving neutron. More neutrons are released by the fission. These neutrons strike the nuclei of other uranium-235 atoms, which causes a chain reaction. U Uranium-235 (fissionable) 235 92 U Uranium-236 (very unstable) 236 92 Ba Barium-142 142 56 Kr Krypton-91 91 36 3 n 1010 Neutron </li> <li> Slide 6 </li> <li> 25.3 Fission and Fusion &gt; 6 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Nuclear Fission In a chain reaction, some of the emitted neutrons react with other fissionable atoms, which emit neutrons that react with still more fissionable atoms. </li> <li> Slide 7 </li> <li> 25.3 Fission and Fusion &gt; 7 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Nuclear Fission Nuclear fission can release enormous amounts of energy. The fission of 1 kg of uranium-235 yields an amount of energy equal to that produced when 20,000 tons of dynamite explode. An atomic bomb is a device that can trigger an uncontrolled nuclear chain reaction. </li> <li> Slide 8 </li> <li> 25.3 Fission and Fusion &gt; 8 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Nuclear Fission Nuclear reactors use controlled fission to produce useful energy. The reaction takes place within uranium- 235 or plutonium-239 fuel rods. A coolant absorbs heat produced by the controlled fission reaction and transfers the heat to water, which changes to steam. The steam drives a turbine, which drives a generator that produces electricity. </li> <li> Slide 9 </li> <li> 25.3 Fission and Fusion &gt; 9 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Nuclear Fission Nuclear reactors use controlled fission to produce useful energy. </li> <li> Slide 10 </li> <li> 25.3 Fission and Fusion &gt; 10 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. How does the fission of a uranium-235 nucleus cause a chain reaction? When slow-moving neutrons bombard uranium- 235, the atom splits and releases more neutrons. These neutrons then collide with more uranium atoms, and so on. </li> <li> Slide 11 </li> <li> 25.3 Fission and Fusion &gt; 11 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Nuclear Fusion How do fission reactions and fusion reactions differ? </li> <li> Slide 12 </li> <li> 25.3 Fission and Fusion &gt; 12 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Nuclear Fusion The energy emitted by the sun results from nuclear fusion. Fusion occurs when nuclei combine to produce a nucleus of greater mass. </li> <li> Slide 13 </li> <li> 25.3 Fission and Fusion &gt; 13 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Nuclear Fusion The energy emitted by the sun results from nuclear fusion. Fusion occurs when nuclei combine to produce a nucleus of greater mass. In solar fusion, hydrogen nuclei (protons) fuse to make helium nuclei. </li> <li> Slide 14 </li> <li> 25.3 Fission and Fusion &gt; 14 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Nuclear Fusion The energy emitted by the sun results from nuclear fusion. Fusion occurs when nuclei combine to produce a nucleus of greater mass. In solar fusion, hydrogen nuclei (protons) fuse to make helium nuclei. The reaction also produces two positrons. </li> <li> Slide 15 </li> <li> 25.3 Fission and Fusion &gt; 15 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Nuclear Fusion Fusion reactions, in which small nuclei combine, release much more energy than fission reactions, in which large nuclei split apart and form smaller nuclei. </li> <li> Slide 16 </li> <li> 25.3 Fission and Fusion &gt; 16 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Key Concepts In a chain reaction, some of the emitted neutrons react with other fissionable atoms, which emit neutrons that react with still more fissionable atoms. Fusion reactions, in which small nuclei combine, release much more energy than fission reactions, in which large nuclei split apart to form smaller nuclei. </li> <li> Slide 17 </li> <li> 25.3 Fission and Fusion &gt; 17 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Glossary Terms fission: the splitting of a nucleus into smaller fragments, accompanied by the release of neutrons and a large amount of energy neutron moderation: a process used in nuclear reactors to slow down neutrons so the reactor fuel captures them to continue the chain reaction </li> <li> Slide 18 </li> <li> 25.3 Fission and Fusion &gt; 18 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Glossary Terms neutron absorption: a process that decreases the number of slow-moving neutrons in a nuclear reactor; this is accomplished by using control rods made of a material such as cadmium, which absorbs neutrons fusion: the process of combining nuclei to produce a nucleus of greater mass </li> <li> Slide 19 </li> <li> 25.3 Fission and Fusion &gt; 19 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. Electrons and the Structure of Atoms During fission and fusion, atoms change their chemical identity as the number of protons in their nuclei change. In fission, large nuclei split into two or more smaller nuclei. In fusion, smaller nuclei combine to form larger nuclei at extremely high temperature and pressure. BIG IDEA </li> <li> Slide 20 </li> <li> 25.3 Fission and Fusion &gt; 20 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. END OF 25.3 </li> </ul>

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