1. Chapter 19a Radioactivity and Nuclear Energy

2. Chapter 19 Table of Contents Copyright © Cengage Learning. All rights reserved 2 19.1Radioactive Decay 19.2 Nuclear Transformations 19.3 Detection of Radioactivity and the Concept of Half-life 19.4Dating by Radioactivity 19.5Medical Applications of Radioactivity

3. Section 19.1 Radioactive Decay Return to TOC Copyright © Cengage Learning. All rights reserved 3 Review nucleons – particles found in the nucleus of an atom  neutrons  protons atomic number (Z) – number of protons in the nucleus mass number (A) – sum of the number of protons and neutrons isotopes – atoms with identical atomic numbers but different mass numbers nuclide – each unique atom

4. Section 19.1 Radioactive Decay Return to TOC Copyright © Cengage Learning. All rights reserved 4 Radioactive Decay radioactive – nucleus which spontaneously decomposes forming a different nucleus and producing one or more particles nuclear equation – shows the radioactive decomposition of an element Paper Wood Lead

5. Section 19.1 Radioactive Decay Return to TOC Copyright © Cengage Learning. All rights reserved 5 Types of Radioactive Decay – Alpha Particle Production Alpha particle – helium nucleus  Examples Net effect is loss of 4 in mass number and loss of 2 in atomic number.

6. Section 19.1 Radioactive Decay Return to TOC Copyright © Cengage Learning. All rights reserved 6 Types of Radioactive Decay – Beta Particle Production Beta particle – electron  Examples Net effect is to change a neutron to a proton.

7. Section 19.1 Radioactive Decay Return to TOC Copyright © Cengage Learning. All rights reserved 7 Types of Radioactive Decay – Gamma Ray Release Gamma ray – high energy photon  Example Net effect is no change in mass number or atomic number.

8. Section 19.1 Radioactive Decay Return to TOC Copyright © Cengage Learning. All rights reserved 8 Types of Radioactive Decay – Positron Production Positron – particle with same mass as an electron but with a positive charge  Example Net effect is to change a proton to a neutron.

9. Section 19.1 Radioactive Decay Return to TOC Copyright © Cengage Learning. All rights reserved 9 Types of Radioactive Decay – Electron Capture Process in which one of the inner-orbital electrons is captured by the nucleus.  Example

10. Section 19.1 Radioactive Decay Return to TOC Copyright © Cengage Learning. All rights reserved 10 Various Types of Radioactive Processes

11. Section 19.1 Radioactive Decay Return to TOC Copyright © Cengage Learning. All rights reserved 11 Decay Series Occurs until a stable nuclide is formed.

12. Section 19.1 Radioactive Decay Return to TOC Copyright © Cengage Learning. All rights reserved 12 Concept Check Which of the following produces a particle? electron capture positron alpha particle beta particle

13. Section 19.2 Return to TOC Nuclear Transformations Copyright © Cengage Learning. All rights reserved 13 Change of one element to another Bombard elements with particles  Examples

14. Section 19.2 Return to TOC Nuclear Transformations Copyright © Cengage Learning. All rights reserved 14 Transuranium Elements Elements with atomic numbers greater than 92 which have been synthesized.

15. Section 19.2 Return to TOC Nuclear Transformations Copyright © Cengage Learning. All rights reserved 15 Concept Check If the bombardment of with alpha particles leads to the emission of a neutron, which nuclide is formed in this nuclear transformation process?

16. Section 19.3 Return to TOC Detection of Radioactivity and the Concept of Half-life Copyright © Cengage Learning. All rights reserved 16 Geiger–Mϋller Counter Instrument which measures radioactive decay by registering the ions and electrons produced as a radioactive particle passes through a gas-filled chamber.

17. Section 19.3 Return to TOC Detection of Radioactivity and the Concept of Half-life Copyright © Cengage Learning. All rights reserved 17 Scintillation Counter Instrument which measures the rate of radioactive decay by sensing flashes of light that the radiation produces in the detector.

18. Section 19.3 Return to TOC Detection of Radioactivity and the Concept of Half-life Copyright © Cengage Learning. All rights reserved 18 Discovery of Po and Ra Marie Skłodowska Curie (1867-1934) Marie, and her husband Pierre, analyzed a ton of Uranium ore. After removing the uranium the radioactivity increased. This led to the discovery of Polonium, more radioactive than uranium, named after here home country of Poland. After removing the Polonium the radioactivity increased again. This led to the discovery of a small amount in their hand of Radium, so radioactive that it glowed in the dark.

19. Section 19.3 Return to TOC Detection of Radioactivity and the Concept of Half-life Copyright © Cengage Learning. All rights reserved 19 Half-life Time required for half of the original sample of radioactive nuclides to decay.

20. Section 19.3 Return to TOC Detection of Radioactivity and the Concept of Half-life Copyright © Cengage Learning. All rights reserved 20 Concept Check Strontium-90 is a by-product of nuclear fission and a contaminant associated with the testing of nuclear weapons. It is of particular concern to humans because it tends to become concentrated in bones, substituting for calcium (similar ionic radius and both 2+ ionic charge). The half-life of is 29 years. If milk contaminated with is ingested, after 58 years what percentage of the replacing Ca in bones would remain to continue emitting beta particles? a)100% b)75% c)50% d)25%

21. Section 19.4 Dating by Radioactivity Return to TOC Copyright © Cengage Learning. All rights reserved 21 Radiocarbon Dating (Carbon-14 Dating) Originated in 1940s by Willard Libby  Based on the radioactivity of carbon-14 Used to date wood and artifacts

22. Section 19.5 Medical Applications of Radioactivity Return to TOC Copyright © Cengage Learning. All rights reserved 22 Radiotracers Radioactive nuclides that can be introduced into organisms and traced for diagnostic purposes.

23. Section 19.5 Medical Applications of Radioactivity Return to TOC Copyright © Cengage Learning. All rights reserved 23 Radon –A rare noble gas which has also been implicated as a possible cause of lung cancer. –Accumulates in houses from particular kinds of soils or rock strata. 15-

24. Section 19.5 Medical Applications of Radioactivity Return to TOC Copyright © Cengage Learning. All rights reserved 24 Predicted Indoor Radon Levels 15- red zones-greater than 4 pCi/L orange zones-between 2 and 4 pCi/L yellow zones-less than 2 pCi/L Santa Barbara/ Ventura Counties highest levels

25. Section 19.5 Medical Applications of Radioactivity Return to TOC Copyright © Cengage Learning. All rights reserved 25 Chapter 19b Radioactivity and Nuclear Energy W

26. Section 19.5 Medical Applications of Radioactivity Return to TOC Copyright © Cengage Learning. All rights reserved 26 19.6Nuclear Energy 19.7Nuclear Fission 19.8Nuclear Reactors 19.9Nuclear Fusion 19.10Effects of Radiation Predicted Indoor Radon Levels

27. Section 19.6 Nuclear Energy Return to TOC Copyright © Cengage Learning. All rights reserved 27 Two types of nuclear processes can produce energy.  Combining two light nuclei to form a heavier nucleus - fusion  Splitting a heavy nucleus into two nuclei with smaller mass numbers - fission Iron has the most stable nucleus

28. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 28 Releases 2.1  10 13 J/mol of uranium-235 Each fission produces 3 neutrons.

29. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 29 Chain reaction – self sustaining fission process caused by the production of neutrons that proceed to split other nuclei Critical mass – mass of fissionable material required to produce a chain reaction

30. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 30 A Schematic Diagram of a Nuclear Power Plant

31. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 31 Nuclear energy generates about 21 percent of the electricity produced in the United States. Questions of safety, costs, and nuclear waste disposal have halted construction of nuclear reactors in the United States.

32. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 32 Nuclear Power plants locations throughout the world.

33. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 33 Disposal of Radioactive Waste Where can you dispose of radioactive waste where it will be safe? In the ground as shown to the right? Into space? Into the Sun?

34. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 34 Plutonium When nonfissionable U-238 captures a fast neutron, it eventually forms the fissionable nuclide of plutonium, Pu-239, which can support a chain reaction. Plutonium is a transuranium element, meaning that it has an atomic number greater than the 92 of uranium. The fissionable plutonium produced in a uranium-fueled reactor can be used as a fuel or in nuclear weapons. Little Boy Fatman

35. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 35 Nuclear Bombs Trinity Bomb Hiroshima http://www.youtube.com/watch?v=NpbCZ8QRpEg&NR=1 http://www.metacafe.com/watch/40 0824/trinity_nuclear_weapon_test/ Equivalent to 12-15 kilotons of TNT

36. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 36 Hiroshima Imprint of sitting person 70,000 killed immediately and 70,000 more later. Half from blast, a third radiation and rest from radioactivity.

37. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 37 Nagasaki Equivalent to 20-22 kilotons of TNT Compare to the Tsar Bomb dropped in 1961 that was equivalent to 51 megatons of TNT or 50,000 kt of TNT.

38. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 38 Process of combining 2 light nuclei Produces more energy per mole than fission Powers the stars and sun Nuclear Fusion

39. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 39 Requires extremely high temperatures Currently not technically possible for us to use as an energy source Nuclear Fusion

40. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 40 Nuclear fusion produces tremendous quantities of energy and has the potential of becoming the ultimate source of energy on earth. Nuclear Fusion

41. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 41 Biological Effects of Radiation Depend on: 1.Energy of the radiation 2.Penetrating ability of the radiation 3.Ionizing ability of the radiation 4.Chemical properties of the radiation source

42. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 42 Effects of Short–Term Exposures to Radiation

43. Section 19.7 Nuclear Fission Return to TOC Copyright © Cengage Learning. All rights reserved 43 Typical Radiation Exposures for a Person Living in the U.S.