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Nuclear Chemistry

Nuclear Chemistry. Chapter 16 Tech Prep Chapter 25 College Prep Chapter 18 Honors. Protons Neutrons Quarks Nucleons * Atomic Number Mass Number Isotopes Nuclide * *(honors only). Thermodynamic Stability * Kinetic Stability * Radioactive Decay Alpha Particles Beta Particles

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Nuclear Chemistry

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  1. Nuclear Chemistry Chapter 16 Tech Prep Chapter 25 College Prep Chapter 18 Honors

  2. Protons Neutrons Quarks Nucleons * Atomic Number Mass Number Isotopes Nuclide * *(honors only) Thermodynamic Stability* Kinetic Stability * Radioactive Decay Alpha Particles Beta Particles Gamma Particles Zone of Stability * Key Terms

  3. Indicator C-2.5Compare alpha, beta, and gamma radiation in terms of mass, charge, penetrating power, and the release of these particles from the nucleus. • Radioactive nuclei that undergo decomposition falls into two categories: • change in mass number of the decaying nucleus • and those that do not change the mass number.

  4. Alpha Radiation • Mass number changes • helium nuclei from a radioactive source; 2 protons and 2 neutrons; double positive charge. • Common for heavy nuclides • α-particle, __He • 2 α-particle producers: U-238 and Th-230

  5. Beta Radiation • Mass number remains constant • β particles (electron) , __e • fast moving electrons formed from the decomposition of a neutron, negative charge. • Th-234 and I-131 are beta producers. • Neutron changes to a proton.

  6. Gamma Radiation • γ high-energy electromagnetic radiation given off by a radioisotope, no charge, no mass. • Frequently accompanies nuclear decays and particle reactions • Example: α-particle of U-238 (see page 880).

  7. Alpha Beta Gamma    Penetrating Power

  8. Alpha Beta Gamma Low (0.05 mm) body tissue; shielding – paper, clothing Moderate (4mm) body tissue; Shielding – metal foil Very high – penetrates body easily; shielding – lead, concrete (incomplete) Penetrating Power

  9. Indicator C-2.4 • Compare the nuclear reactions of fission and fusion to chemical reactions (including the parts of the atom involved and the relative amounts of energy released). • What is fission and fusion?

  10. Fission • splitting of nuclei of certain isotopes into smaller fragments with similar mass numbers. Ex. U-235 and Pu-239 • Fission is used in nuclear reactor to produce energy. • It has to be controlled in the reactor. Controlling the reaction involves 2 steps: • 1. Neutron moderation – reduces the speed of neutrons. • 2. Neutron absorption – decreases the # of slow moving neutrons.

  11. Fusion • (thermonuclear rxn.) – combining nuclei to produce a more stable nucleus of greater mass. • Solar fusion hydrogen (protons) nuclei fuse to make helium nuclei. • Nuclear Fusion occurs at extremely high temperature.

  12. EQ - How does the nuclear reactions of fission and fusion compare to chemical reactions (including the parts of the atom involved and the relative amounts of energy released)? • What parts are involved for nuclear rxns? • What parts are involved in chemical rxns? • How does the energy released compare between the two reactions? Hint: p. 897(honors)

  13. C-2.6 Explain the concept of half-life, its use in determining the age of materials, and its significance to nuclear waste disposal.What is half-life and why is it important?

  14. Answer • Half-life (t1/2) is the time required for one-half of the nuclei of a radioisotope sample to decay to products.

  15. Answer • Half-life (t1/2) is the time required for one-half of the nuclei of a radioisotope sample to decay to products. • Carbon dating is important for determining the age of materials. All living things contain C-12 and C-14 in fixed ratios. The ratio changes when an organism dies, thus the C-14 decays to N -14. The ratio changes.

  16. Answer • Half-life (t1/2) is the time required for one-half of the nuclei of a radioisotope sample to decay to products. • Carbon dating is important for determining the age of materials. All living things contain C-12 and C-14 in fixed ratios. The ratio changes when on organism dies, thus the C-14 decays to N -14. The ratio changes. • Chemical waste may be hazardous. However, nuclear waste is even more hazardous because of the time-frame and the radiation. Only time can make nuclear waste not radioactive

  17. Calculating amount of material remaining using half-life: A = A0 x (1/2)n A0 = 1.0 g, n=4 [10.4/2.6=4] A = 1.0 g x (1/2)4 A = 1.0 g x 1/16 = 0.063 g Where A0 is initial weight A is final weight (amount) n is the number of half-lives. {n= Time passed ÷ half life} • Refer to figure 18.3 (page 885).

  18. Logical Method

  19. BW: Half-life Problems • #1 A patient is administered 40.0 mg of iodine-131 to assess the thyroid. How much of this nuclide will remain in the body after 40 days if the half-life is of iodine-131 is 8 days? • #2 A patient is administered 100. mg of xenon-133 to assess the lungs. How much of this nuclide will remain in the body after 21.2 days if the half-life is of xenon-133 is 5.3 days?

  20. Answers • #1. A = A0 x (1/2)nn = 40/8 = 5 half-lives A= 40.0 mg x (1/2)5 = 40.0 mg x (1/32) = 1.25 mg • #2.A = 100. mg x (1/2) 4n = 21.2/5.3 = 4 half-lives A = 100. mg x (1/16) = 6.25 mg

  21. Indicator C-2.8 Analyze a decay series chart to determine the products of successive nuclear reactions and write nuclear equations for disintegration of specified nuclides.

  22. Refer to Table 18.3on page 886The Half-lives of Nuclides in the U-238 Decay Series. • Answer the following questions. • What nuclides have the following half-life? a.) 5.0 days b.) 2.48 x 105 years c.) 3.1 minutes d.) 1.62 x 103 years • What is the particle produced from the above nuclides?

  23. Answers • What nuclides have the following half-life? a.) bismuth-210 b.) uranium-234 c.) polonium-218 d.) radium-226 • What is the particle produced from the above nuclides? a.) beta b.) alpha c.) alpha d.) alpha

  24. Write the nuclear equations for disintegration of specified nuclides. • U-238 • Ra-226 • Pb-214 • See page 880, Table 18.2 for more equations.

  25. 3 devices used to measure the ionization radiation: Geiger counter - beta radiation Scintillation counter – all types Film badges – all types. Uses of Radiation: 1. Art 2. Crime labs 3. Agriculture 4. Diagnosing diseases 5. Treating diseases Detecting Radiation:Radiation emitted from isotopes and x-rays are forms of ionization radiation. It has enough energy to knock electrons off of some atoms. It cannot be detected by one’s senses.

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