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Unit 2 Organization of Matter Ch 22 - Nuclear Chemistry WDYT What is one of the ways in which we designate the n

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Unit 2 Organization of Matter Ch 22 - Nuclear Chemistry WDYT What is one of the ways in which we designate the n

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    1. Unit 2 – Organization of Matter Ch 22 - Nuclear Chemistry WDYT? – What is one of the ways in which we designate the nucleus of an isotope? Show me the isotope that is used as the standard for the amu…

    2. Section 22-1: The Nucleus Nucleons: Nuclide: Nuclide format: any of 3 formats a. b. c.

    3. Mass Defect and Nuclide Stability Consider an isotope of helium…

    4. E = mc2 (or BE) m = 1 amu = 1.6605 x 10-27 kg new c.f.! c = c2 = 1 Joule (J) = Add electrons ONLY if you’re calculating binding energy for formation of entire atom Nuclear Binding Energy (E)

    5. Calculate the Binding Energy for the formation of the He atom Recall the mass defect (m): Convert m to kg: 0.03038 amu x 1.6605 x 10-27 kg = 1 amu E = mc2 = ( )(9.0 x 1016 m2/s2) = =

    6. We can also use the binding energy equation to determine the amount of energy released in a nuclear reaction: 1H + 7Li ? 2 4He + (energy)

    7. Binding Energy per Nucleon What does per mean? What is a nucleon? What is the significance of BE/nucleon?

    8. Practice Problems 1. Calculate the binding energy for a mole of 16O atoms. The atomic mass is 15.995 amu. 2. Calculate the binding energy per nucleon of a 55Mn atom. The atom’s atomic mass is 54.938 amu. Problems 25-30 in your textbook (pg 723-724) are additional practice problems

    9. WDYT? Do we balance NUCLEAR reactions in the same manner in which we balance other CHEMICAL reactions? If the method is different, explain HOW is it different? Does the law of conservation of mass apply?

    10. Nuclear reactions Nuclear reaction: Transmutation: How to balance nuclear reactions: Think of the arrow as an equal sign conservation of mass number (p + n ) conservation of protons (atomic number)

    11. Try these!

    12. Section 22-2: Radioactive Decay Radioactive Decay: Nuclear Radiation: Radioactive Nuclide (a.k.a. radionuclide, radioisotope): All of the nuclides beyond atomic number are unstable and therefore radioactive

    13. Types of Radioactive Particles

    14. Nuclear Reaction Terminology

    15. Sample Nuclear Reactions Alpha Emission (alpha decay) Beta Emission (beta decay) Positron Emission Electron Capture Gamma Emission Neutron bombardment K-capture (this is a when an electron is captured from inside the atom itself!)

    17.

    18. WDYT? Is the “half-life” of a radionuclide when the isotope has a mid-life crisis? Do all nuclides have half-lives? Is there such a thing called a whole life? If we continue to HALF a sample, can we ever use up the entire sample?

    19. Half-life Half-life: (t½) St amt ½ left ¼ left ? left time first second third half-life half life half life 100 g 50 g 25 g 12.5 g 10 sec 20 sec 30 sec t½=

    20. Half-life St amt ½ left ¼ left ? left 16 g 8 g 4 g 2 g 1 t½ 2 t½ 3 t½ ? sec Percentage changed? 0% Fraction changed? 0 Percentage Left? 100%

    21. Represented Pictorially

    22. So, How do we solve Half-life Problems? 1. Either, we can figure it out with common sense…or… 2. We can use the following equations: number of half-lives passed (n) = time elapsed half-life amt of sample left = original amt x (½)n part = fraction part x 100 = percent whole whole

    23. 1. The half-life of iodine-131 is 8.040 days. What percentage of an iodine-131 sample will remain after 40.2 days? 2. Uranium-238 decays through alpha decay with a half-life of 4.46 x 109 years. How long would it take for ? of a sample of uranium-238 to decay?

    24. 3. What percentage of argon-39 has decayed after 7.95 x 102 years if its half-life is 265 years? 4. A rock sample contained 24.0 g of In-115. The half-life of In-115 is 4.0 days. Determine the time when only 3.0 g of In-115 remains.

    25. 5. The half-life of a radioactive isotope is 6.0 hours. After 8 half-lives, how much of a 1.0-mg sample will remain?

    26. WDYT? Why is radioactivity relevant to your life? What is the connection between what we’re learning in the classroom and your future (or your past)? What are the benefits of radioactivity? What are the dangers of radioactivity?

    27. Decay series Decay Series: Parent nuclide: Daughter nuclide:

    29. Sample Problem Pu-239 is formed from U-238 by three successive nuclear reactions. In the first reaction, a neutron is captured. The second and third involve beta decay. Write the decay series.

    30. Artificial Nuclides Transuranium Elements: All of the nuclides beyond atomic number__ __ are artificially prepared (synthetic; made in a lab)

    31. Nuclear Fission and Fusion Click this link and begin at card 80… http://www.hcc.mnscu.edu/programs/dept/chem/V.11/index.html You might consider checking out the rest of the cards on your own time…

    32. Some important items to familiarize yourself with… Radiocarbon dating and how it works The relationship between critical mass and chain reaction The function of the control rods in a nuclear reactor Compare and contrast fission and fusion “Where? How?” you ask… the book…those cards…another website…

    33. Chain reaction

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