1 / 23

NUCLEAR CHEMISTRY

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

steel-salazar
Download Presentation

NUCLEAR CHEMISTRY

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NUCLEAR CHEMISTRY nuclear chemistry/physics: processes that occur in the NUCLEUS—these are not chemical reactions!

  2. Objectives • What 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.

  3. Radioactivity • 1896: Henri Becquerel discovers that uranium affects photographic film. • Marie Curie calls it radioactivity: the process of materials emitting “rays” • radiation: the rays/particles given off by a radioactive source • radioisotope: unstable isotope that emits radiation

  4. Three Types of Radiation • a: Alpha (helium nucleus emitted) Total charge (subscript) and mass (superscript) must be conserved. • b: Beta (electrons emitted as no → p++ e-) • g: Gamma (high energy EM radiation)

  5. Radiation Problems

  6. Objectives • Why 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.

  7. Nuclear Stability • Protons 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. 1:1.5 1:1

  8. Transmutations • transmutation: an atom is converted into a different atom (a different element) • occurs through radioactive decay *positron: positive electron (antimatter) *neutrino (v): may be massless (nucleus is too heavy) (too many neutrons) (too many protons)

  9. Decay Series

  10. Transmutations • bombardment: particles collides with the nucleus to cause transmutations (like bowling!) Rutherford The discovery of the p+ and the no were achieved using bombardment.

  11. Objectives • How 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.

  12. Half-Life • half-life (T1/2): the time it takes for one-half of the nuclei of a radioisotope to decay to products • 64 nuclei → 32 → 16 → 8 → 4 → 2 → 1 • If T1/2 = 200 years, it takes six half-lives (1200 years) to decay from 64 to 1.

  13. Measuring Nuclear Decay • Fermium has a half-life of 100.5 days. How much of a 5.2 mg sample of fermium will remain after 365 days?

  14. Objectives • What 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.

  15. Nuclear Fission • fission: the splitting of a large nucleus • products have less mass than reactants • mass is converted into energy (E=mc2)

  16. Nuclear Fission Power • Nuclear power plants use controlled nuclear fission to release energy slowly. • Heat creates steam that generates electricity.

  17. Fission Reactor Core

  18. Three-Mile Island

  19. Chernobyl

  20. The Fission A-Bomb • The 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

  21. Nuclear Fusion • nuclear fusion: small nuclei combine and release much more energy than fission reactions. • occurs in the sun and nuclear weapons

  22. Thermonuclear Weapons • Modern “nukes” use fission to start a fusion reaction. • 100 times more powerful than the A-bomb (1.2 megatons vs. 15 kilotons of TNT).

More Related