NUCLEAR CHANGES

1. NUCLEAR CHANGES

2. Chapter 9 Nuclear Radiation • Radioactivity: • process by which an unstable nucleus emits one or more particles or energy in the form of electromagnetic radiation. • nuclear radiation: • particles that are released from nucleus during radioactive decay.

3. ALPHA PARTICLES • alpha particles • consists of two protons and two neutrons • Composed of He nucleus atom w/ +2 charge • Least penetrating type of radiation • Can be stopped by a sheet of paper

4. BETA PARTICLES • beta particle: • negatively charged electron emitted during certain types of radioactive decay • Emitted at high speeds from nucleus

5. GAMMA PARTICLES • gamma ray • high-energy photon emitted by a nucleus during fission and radioactive decay. • Most penetrating type of radiation • Does not have a charge nor mass • Neutron emission consists of matter that is emitted from an unstable nucleus. • Neutrons are able to travel farther through matter than either alpha or beta particles.

6. Chapter 9 Nuclear Fission • Fission: • process by which a nucleus splits into two or more fragments and releases neutrons and energy. • Produces nuclei of lower mass than reactants • Used to produce nuclear power (electricity) • Produces extremely toxic waste

7. A. Nuclear Power • Fission Reactors

8. Cooling Tower A. Nuclear Power • Fission Reactors

9. A. Fission • splitting a nucleus into two or more smaller nuclei • some mass is converted to large amounts of energy

10. A. Fission • chain reaction - self-feeding reaction

11. B. Fusion • combining of two nuclei to form one nucleus of larger mass • produces even more energy than fission • occurs naturally in stars

12. 235U is limited danger of meltdown toxic waste thermal pollution Hydrogen is abundant no danger of meltdown no toxic waste not yet sustainable A. Nuclear Power FISSION FUSION vs.

13. Chapter 9 Nuclear Fusion • Fusion: • process in which light nuclei combine at extremely high temperature, forming heavier, more stable nuclei and releasing energy. • Produces nuclei of higher mass than reactants • Takes place in the sun. • Helium is major by product

14. A. Nuclear Power • Fusion Reactors (not yet sustainable) National Spherical Torus Experiment Tokamak Fusion Test Reactor Princeton University

15. A. Nuclear Power • Fusion Reactors (not yet sustainable)

16. Beneficial Uses of Nuclear Radiation • Smoke detectors • small alpha-emitting isotope detects smoke particles in the air. • Nuclear radiation is used to detect diseases. • radioactive tracer: • radioactive material that is added to a substance so that its distribution can be detected later.

17. Chapter 9 Beneficial Uses of Nuclear Radiation • Nuclear radiation therapy is used to treat cancer. • Radiotherapy: • treatment that uses controlled doses of nuclear radiation for treating diseases such as cancer. • Agriculture uses radioactive tracers and radio-isotopes. • understand biochemical processes in plants.

18. Possible Risks of Nuclear Radiation • Nuclear radiation can ionize atoms. • Ionization is a change in the number of electrons in an atom or molecule, causing the particle to be positively or negatively charged. • Radiation sickness results from high levels of nuclear radiation. • People working in radioactive areas wear a dosimeter, a device that measures the amount of nuclear radiation exposure. • Studies have shown a relationship between exposure to high levels of nuclear radiation and cancer.

19. Chapter 9 Possible Risks of Nuclear Radiation • The risk depends upon the amount of radiation exposure. • High concentrations of radon gas can be hazardous. • Radon gas: • colorless and odorless, • produced by the decay of uranium-238 • naturally occurs in soil and rock.

20. CHAPTER24 Nuclear Energy II. Nuclear Reactions (p.689-691)

21. A. Fission • splitting a nucleus into two or more smaller nuclei • some mass is converted to large amounts of energy

22. A. Fission • chain reaction - self-feeding reaction

23. B. Fusion • combining of two nuclei to form one nucleus of larger mass • produces even more energy than fission • occurs naturally in stars

24. CHAPTER24 Nuclear Energy I. Radioactivity (p.674-683)

25. A. Definitions • Radioactivity • emission of high-energy radiation from the nucleus of an atom • Nuclide • nucleus of an isotope • Transmutation • process of changing one element into another via nuclear decay

26. B. Types of Radiation • Alpha () • helium nucleus paper 2+ • Beta-minus (-) • electron lead 1- • Gamma () • high-energy photon concrete 0

27. C. Nuclear Decay • Why nuclides decay… • to obtain a stable ratio of neutrons to protons Stable Unstable (radioactive)

28. C. Nuclear Decay TRANSMUTATION • Alpha Emission • Beta Emission

29. Example Half-lives polonium-194 0.7 seconds lead-212 10.6 hours iodine-131 8.04 days carbon-14 5,370 years uranium-238 4.5 billion years D. Half-life • Half-life (t½) • time it takes for half of the nuclides in a sample to decay

30. D. Half-life • How much of a 20-g sample of sodium-24 would remain after decaying for 30 hours? Sodium-24 has a half-life of 15 hours. GIVEN: total time = 30 hours t1/2 = 15 hours original mass = 20 g WORK: number of half-lives = 2 20 g ÷ 2 = 10 g (1 half-life) 10 g ÷ 2 = 5 g (2 half-lives) 5 g of 24Na would remain.

31. CHAPTER24 Nuclear Energy III. Applications (p.704-708)

32. Cooling Tower A. Nuclear Power • Fission Reactors

33. A. Nuclear Power • Fission Reactors

34. A. Nuclear Power • Fusion Reactors (not yet sustainable)

35. A. Nuclear Power • Fusion Reactors (not yet sustainable) National Spherical Torus Experiment Tokamak Fusion Test Reactor Princeton University

36. 235U is limited danger of meltdown toxic waste thermal pollution Hydrogen is abundant no danger of meltdown no toxic waste not yet sustainable A. Nuclear Power FISSION FUSION vs.

37. B. Others • Choose one of the following to investigate: • Irradiated Food (p.676) • Radioactive Dating (p.683) • Nuclear Medicine (p.692-693) • Make a mini-poster to display what you have learned.