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Nuclear Chemistry

Dive into the world of nuclear chemistry and discover the fascinating properties of radioactivity. Learn about the discovery of uranium, the lives of Marie and Pierre Curie, the different types of radiation, and the various uses of nuclear chemistry in everyday life.

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Nuclear Chemistry

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  1. Nuclear Chemistry Applied Chemistry

  2. When you think of the word NUCLEAR, what does it bring to mind?

  3. Radioactivity Discovery • In 1896, Henri Becquerel noticed that a piece of uranium ore, called pitchblende, exposed a piece of photographic film. • Uranium gave off invisible rays he called uranic rays. • Uranium is radioactive.

  4. Marie & Pierre Curie: 1903 • Shared the Nobel Prize in Chemistry with Becquerel. • They discovered 2 new radioactive elements, Radium and Polonium. • Marie called Radium the “radiant” element and Polonium she named for her native Poland. • How do you think Marie & Pierre died??? 1867-1934 1859-1906

  5. What happened to The Curies? • Pierre was run over by a horse-drawn wagon in Paris and killed in 1906. Marie was left alone with two daughters, aged 2 and 9. • In 1911 she went on to win a second Nobel Prize in chemistry. • In 1934, Marie died of leukemia brought on by radiation exposure one year before her daughter and son-in-law won the Nobel Prize for Chemistry.

  6. Radioactivity • Radioactivity is the release of particles, energy, or both from the nucleus of an atom.

  7. Radioactivity • Natural radioactivity is found on the earth. • Everyone receives background radiation at low levels from cosmic radiation, ground, building materials, and food. • Exposure to radiation does not make you or anything else radioactive. • Artificial radioactivity is produced in the lab.

  8. Types of Radiation -Energy • Nonionizing radiation is radiation with low energy. • Ex: radiowaves, infrared, and visible light • Ionizing radiation is radiation with high energy. • Ex: ultraviolet, x-ray, and gamma

  9. Types of Radiation - Energy • Particles released from the nucleus of an atom. • Examples: alpha and beta particles

  10. Characteristics of Radiation 2 protons & 2 neutrons Helium nuclei Low Sheet of paper  Medium An electron Aluminum Foil  High Energy High Thick concrete or lead 

  11. Nuclear Radiation Penetrating Power

  12. Exposure and Uses of Radiation - Radon • Radon is a decay product of uranium found in the soil or bedrock. • This is natural radioactivity. • Radon is a colorless, odorless gas. • Some radon produced in the soil dissolves in groundwater.

  13. Radon • Many houses have cracks in the foundation and basement floors that permit radon to collect and concentrate. • Most radon enters your body by breathing. • Radon decays by alpha emission to produce heavy metals. • These heavy metals are not exhaled and produce damaging alpha particles in your body.

  14. How Radon Gas Enters your House

  15. Exposure and Uses of RadiationRadon • Radon in your home can be checked by you. • Increased ventilation and sealing cracks in the floors are 2 ways you can reduce radon exposure.

  16. Testing Methods for Radon

  17. Ways to Remove Radon Gas from Your Home

  18. External view of a Radon mitigation system from a home basement. • Below is a view of the fan inside which runs 24 hours a day pulling air from under the basement floor.

  19. U.S. Radon Zones

  20. Exposure and Uses of RadiationSmoke Detectors • Smoke detectors use americium as the ionizing source. • Americium emits alpha particles. • Special disposalof smoke detectors is required.

  21. Exposure and Uses of Radiation • Some EXIT signs use tritium or hydrogen-3 instead of electricity. • Aircraft dials • Luminous paints • Wrist watches • The tritium gas is contained in sealed glass tubes. The insides of the tubes are lined with a phosphor. • Low-energy Beta particles (electrons) emitted by the tritium bombard the phosphor, causing it to glow.

  22. Exposure and Uses of RadiationAgricultural and Consumer Product • Many everyday products and food are treated to kill bacteria and insects. • Examples: fruits, poultry, cosmetics, band aids • Products are irradiated with gamma rays from cobalt-60.(used by CFC Logistics in its irradiator) • Irradiated products are notradioactive.

  23. Irradiated Ground Beef

  24. Medical Uses – Diagnostic Equipment • Computer-Axial Tomography scans or CATscans usex-rays to produce cross-sectional images of the brain.

  25. Medical Uses – Diagnostic Equipment • Magnetic Resonance Imaging or MRI uses radiowaves to “see through” bones to produce images of soft tissue.

  26. Medical Uses – Diagnostic Tools using Radioisotope-Tracer studies • Radioisotopes prepared in a nuclear reactor can be used to both treatand detect various medical conditions. • Tracers can be used to followa particular isotope through its normal path in the body to show any abnormalities. • Tracers used in the body will typically have short half-lives.

  27. Radioisotopes found in various parts of the body

  28. Exposure to Radiation

  29. Devices used to measure radioactivity • In the Lab: • Geiger Counter • In the Workplace: • Film badge or Dosimeter

  30. Measurements of RadioactivityUnits • rad measures the absorbed radiation dose • rem measures the ionizing effect on living organisms. • In humans, ionizing radiation is measured in millirem, abbreviated mrem.

  31. Radioactive Dating • Used for determining the age of previously living material. • For material up to 25,000 years old, carbon-14 is used. • For material over 25,000 years old, potassium-40 is used.

  32. Half-Life • Half-Life is the time for halfof the nuclei in a radioactive sample to decay. • Abbreviated: t1/2 • Units can vary from milliseconds to thousands of years.

  33. Half-Life • Example: Plutonium-239 has a half-life of 24,000 years. A sample of this plutonium today will be half gone in 24,000 years. • A 16-g sample today will have a mass of 8 g in 24,000 years. • After another 24,000 years, its mass will be only 4 g.

  34. Half-life Problems(amount problem – how much) • A radioactive element has a half-life of 64 years. You have a 48 g sample of this element. What is its mass in 192 years? t1/2 = 64 yrs initial = 48 g t = 192 yrs final = ? 1st determine the number of half-lives: 2nd divide original mass by 2. How many times? As many as the number of half-lives.

  35. Half-life Problems(time problem – how long/old?) • Another radioactive sample has a half-life of 37.2 minutes. How long will it take for a 55g sample to decay to 3.4g? t1/2 = 37.2 min initial = 55 g t = ? final = 3.4 g 1st - Divide sample by 2 until final mass is reached. 2nd - Multiply t1/2 by the number of half-lives. 37.2 min x 4 = 148.8 min

  36. Half-Life Practice Problems 1. The half-life for fluorine-18 is 109.8 minutes. How long will it take a 3.60 g sample to decay to 0.225 g? t1/2 = 109.8 min initial = 3.60 g total time = ??? final = 0.225 g time problem 1st repeatedly cut your sample mass in half until you have 0.225 g. 3.60 g  1.80 g  0.90 g  0.45 g  0.225 g 1 2 3 4  2nd multiply the half-life by the number of times you cut the sample in half. 109.8 minutes x 4 = 439.2 minutes 2. The half-life for americium-241 is 432 years. How much of a 50 mg sample will remain after 1296 years? t1/2 = 432 yrs initial = 50 mg total time = 1296 yrs final = ??? amount problem 1st find the number of half-lives in 1296 years. 1296 years 432 years = 3 2nd cut your sample mass in half 3 times.     50 mg 25 mg 12.5 mg 6.25 mg 1 2 3

  37. Nuclear Fission • Nuclear Fission is the splittingof a large nucleus in to smaller nuclei of similar size. • A small amount of mass is converted to a large amount of energy.

  38. Nuclear Fission

  39. Nuclear Fission Examples • Atomic bomb uses U-235 or plutonium • 1st military use of an atomic bomb was in Hiroshima, Japan on August 6, 1945 during WWII. • Nuclear Power Plants

  40. Nuclear Fission • A chain reaction occurs when the material used to start the reaction is also produced until the fuel is used up. • In this fission reaction, the fuel is U-235and the starter for the reaction is the neutron. Controlled vs. Uncontrolled Fission Reaction

  41. Nuclear Chain Reaction - Fission Fuel: U-235 or Pu-239 Critical mass for U is 110 lbs Critical Mass is the minimum amount of fissionable material present (the fuel) to sustain a chain reaction.

  42. The first Atomic Bomb is detonated at Trinity Site near Alamogordo, New Mexico on July 16, 1945. Video of 1st Atomic Bomb shows the result of the blast. A wooden house built 1km away from the test site… A Monument stands at the test site today.

  43. “Little Boy”Uranium fission bomb dropped on Hiroshima, Japan by the “Enola Gay” flown by Colonel Paul Tibbets

  44. Hiroshima - August 6, 1945

  45. Nagasaki - August 9, 1945 “Fat Man” – Plutonium Fuel

  46. Hiroshima 1945 & Today

  47. Nuclear Fusion • Nuclear Fusion is the joining of smaller nuclei to form a larger nucleus. • A smallamount of mass is converted into a large amount of energy that is 4-7 times more than a fission reaction.

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