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NUCLEAR CHEMISTRY. nuclear chemistry/physics : processes that occur in the NUCLEUSthese are not chemical reactions!. Objectives. What is radiation? Understand the meaning of terminology related to radioactivity. Know the three main types of nuclear radiation. - PowerPoint PPT Presentation


<p>Nuclear Chemistry</p> <p>NUCLEAR CHEMISTRY</p> <p>nuclear chemistry/physics:processes that occur in the NUCLEUSthese arenot chemical reactions!ObjectivesWhat is radiation? Understand the meaning of terminology related to radioactivity.Know the three main types of nuclear radiation.Be able to write correct nuclear equations.Radioactivity1896: Henri Becquerel discovers that uranium affects photographic film.Marie Curie calls it radioactivity: the process of materials emitting raysradiation: the rays/particles given off by a radioactive sourceradioisotope: unstable isotope that emits radiation</p> <p>Three Types of Radiationa: Alpha (helium nucleus emitted)</p> <p>Total charge (subscript) and mass (superscript) must be conserved.b: Beta (electrons emitted as no p+ + e-)</p> <p>g: Gamma (high energy EM radiation)</p> <p>Radiation Problems</p> <p>ObjectivesWhy do atoms decay? Understand the concept of nuclear stability.Be able to determine the type of radioactive decay based on various circumstances.Be able to determine the products of various transmutation reactions.Nuclear StabilityProtons repel, but the nuclear strong force holds p+ and no together.A stable p+ / no ratio is needed.Elements decay to make a stable ratio.</p> <p>1:11:1.5Transmutationstransmutation: an atom is converted into a different atom (a different element)occurs through radioactive decay </p> <p>*positron: positive electron (antimatter)*neutrino (v): may be massless </p> <p>(nucleus is too heavy)(too many neutrons)(too many protons)Decay Series</p> <p>Transmutationsbombardment: particles collides with the nucleus to cause transmutations (like bowling!)</p> <p>The discovery of the p+ and the no were achieved using bombardment.</p> <p>RutherfordObjectivesHow long does it take for a nucleus to decay? Understand the concept of half-life.Simulate the radioactive decay of an imaginary radioisotope and determine the half-life of the isotope.Be able to make simple half-life calculations.</p> <p>Half-Lifehalf-life (T1/2): the time it takes for one-half of the nuclei of a radioisotope to decay to products</p> <p>64 nuclei 32 16 8 4 2 1</p> <p>If T1/2 = 200 years, it takes six half-lives (1200 years) to decay from 64 to 1.</p> <p>Measuring Nuclear DecayFermium has a half-life of 100.5 days. How much of a 5.2 mg sample of fermium will remain after 365 days?</p> <p>ObjectivesWhat is nuclear energy? Understand the processes of nuclear fission.Be able to discuss how various technologies employ nuclear fission.Be familiar with the process of nuclear fusion.Nuclear Fissionfission: the splitting of a large nucleus products have less mass than reactantsmass is converted into energy (E=mc2)</p> <p>Nuclear Fission Power Nuclear power plants use controlled nuclear fission to release energy slowly.Heat creates steam that generates electricity.</p> <p>Fission Reactor Core</p> <p>Three-Mile Island</p> <p>Chernobyl</p> <p>The Fission A-BombThe WWII bombs used uncontrolled nuclear fission. Material must have a critical mass to explode.Test bomb/Nagasaki: implosion of Pu-239 Hiroshima: gun-type with U-235</p> <p>Nuclear Fusionnuclear fusion: small nuclei combine and release much more energy than fission reactions.</p> <p>occurs in the sun and nuclear weapons</p> <p>Thermonuclear WeaponsModern nukes use fission to start a fusion reaction.100 times more powerful than the A-bomb (1.2 megatons vs. 15 kilotons of TNT).</p>