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Now You See it, Now You Don’t

Now You See it, Now You Don’t. Topics for Today. Alpha/Beta/gamma decay Radioactive decay series Half-life of radioisotopes Radioactive iodine. Readings for Today. What is radioactivity? Section 7.7 More on half life. Section 7.9. Chapter 7. Radioactive decay series, Figure 7.17

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Now You See it, Now You Don’t

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  1. Now You See it, Now You Don’t

  2. Topics for Today • Alpha/Beta/gamma decay • Radioactive decay series • Half-life of radioisotopes • Radioactive iodine

  3. Readings for Today • What is radioactivity? Section 7.7 • More on half life. Section 7.9

  4. Chapter 7 • Radioactive decay series, Figure 7.17 (page 330) Why are radium and thorium found in nature with uranium?

  5. Chapter 11: Nutrition • Minerals: Macro and Micro (page 511) How is iodine utilized in your body?

  6. Table 7.2. What are the differences between alpha, beta, and gamma radiation?

  7. Topics for Wednesday • What are ions? • How is radiation detected? • How do you stop alpha radiation? Beta? Gamma? • Nuclear Medicine

  8. Readings for Wednesday • What are ions? Sections 5.7 and 5.8 Are ions bad for you?

  9. Readings for Wednesday • Hazards Associated with Radioactivity Section 7.8

  10. Readings for Wednesday • How does Nuclear Fission Work? Section 7.2. Just the part about uranium isotopes

  11. Announcements!

  12. PRELAB QUIZ for Week #2 Due BEFORE your lab this week Unlimited number of tries allowed this week only.

  13. Where in Chemistry? Wednesday 10 – 11 am** 12 – 1 pm Thursday 12 – 1 pm 2 – 4 pm 4 – 6 pm Room 2126 1201 # 37 1201 # 37 1201 # 39 1201 # 38 ** Note Change from Syllabus!

  14. Topics for Today • Alpha/Beta/gamma decay • Radioactive decay series • Half-life of radioisotopes • Radioactive iodine

  15. Review – Why are Radioisotopes Dangerous? • They emit high energy particles and / or electromagnetic radiation • These emissions hit other atoms and molecules and ionize them. • The radioactive substance will change its identity.

  16. They emit high energy particles and / or electromagnetic radiation • These emissions hit other atoms and molecules and ionize them. • The radioactive substance will change its identity.

  17. Review • Uranium (eventually) decays to radon. . . So what ?

  18. Review • Uranium = solid. Stuck in a rock and weakly radioactive. • Radon = gas. Free to penetrate into the human lungs and decay.

  19. Uranium = solid. Stuck in a rock and weakly radioactive. • Radon = gas. Free to penetrate into the human lungs and decay. How does uranium “change” into radon?

  20. Uranium Isotopes U-234 trace U-235 0.72% U-238 99.3%

  21. Uranium Isotopes U-234 trace U-235 0.72% U-238 99.3% How does uranium “change” into radon?

  22. The Beginning… U He + Th 238 92 4 2 234 90

  23. The Beginning…Alpha Decay of Uranium U He + Th p n n p 238 92 4 2 234 90 OR α 4 2 A rose by any other name… OR 4 2 He2+

  24. The Beginning…Alpha Decay of Uranium U He + Th 238 92 4 2 234 90 OR Is thorium radioactive? α 4 2

  25. Beta Decay of Thorium Th β + Pa 234 90 0 -1 234 91

  26. Beta Decay of Thorium Th β + Pa 234 90 0 -1 234 91 What is the mass of a beta particle?

  27. Beta Decay of Thorium Th β + Pa 234 90 0 -1 234 91 What is the mass of a beta particle? What is the charge?

  28. Beta (β) Particles High speed electron ejected from the NUCLEUS. Also known as (AKA) β, β, e-, e 0 -1

  29. Beta (β) Particles High speed electron ejected from the NUCLEUS. 1 0 1 1 0 -1 n p + e β particle

  30. Where were we… • Uranium decayed to thorium • Thorium decayed to protactinium

  31. Beta Decay of Thorium Th β + Pa 234 90 0 -1 234 91

  32. Beta Decay of Thorium Th β + Pa + γ 234 90 0 0 0 -1 234 91

  33. Beta Decay of Thorium Th β + Pa + Gamma Ray γ 234 90 0 0 0 -1 234 91

  34. Gamma Radiation Gamma rays are high energy x-rays, a type of electromagnetic radiation γ, γ 0 0 NO Mass NO Charge

  35. Electromagnetic radiation Figure 2.6 (p. 75)

  36. Beta Decay of Thorium Th β + Pa + γ 234 90 0 0 0 -1 234 91

  37. Beta Decay of Thorium Th β + Pa + γ 234 90 0 0 0 -1 234 91 Is protactinium radioactive?

  38. Your turn… • Write the nuclear equation for the beta decay of Pa-234 (with gamma ray)

  39. Beta Decay of Thorium Pa β + U + γ 234 91 0 0 0 -1 234 92 Is uranium-234 radioactive?

  40. Alpha Decay of Uranium U α + Th 234 92 4 2 230 90 You bet (see atomic #)!

  41. Alpha Decay of Thorium Th α + Ra + γ 230 90 4 2 226 88 0 0

  42. Alpha Decay of Thorium Th α + Ra + γ 230 90 4 2 226 88 0 0 How do you know if there will be a gamma ray?

  43. Alpha Decay of Thorium Th α + Ra + γ 230 90 4 2 226 88 0 0 How do you know if there will be a gamma ray? We will tell you!

  44. Alpha Decay of Radium Ra α + Rn + γ 226 88 4 2 222 86 0 0

  45. Alpha Decay of Radium Ra α + Rn + γ 226 88 4 2 222 86 0 0 Finally!

  46. From Lecture #1…

  47. Radon Quiz 1. Radon enters your house from underground. True False

  48. Radiation art True

  49. Shorthand…

  50. U

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