1. Nuclear Radiation nuclear reactions different from other reactions – ________________________________________ ________________________________________ 1

2. Nuclear Radiation in 1895 German physicist Wilhelm Roentgen discovered that invisible rays were emitted when electrons bombarded the surface of certain materials – named these emissions _________________________ Marie & Pierre Curie isolated the 1 st radioactive material – Marie Curie came up with word ‘radioactive’ – Curies won Nobel Prize in 1903 & Marie won another in 1911 2

3. Nuclear Radiation recall from Chapter 4 – nucleus made up of protons and neutrons – atomic # (_____) is the number of protons – mass # (______) is the protons + neutrons – ______________________ are atoms with the same atomic number but different atomic masses (different # of neutrons) – nuclides represented by A = Mass # Z = Atomic # X = Element Symbol 3

4. Nuclear Radiation example – carbon series of isotopes carbon–12 carbon–13 carbon–14 4

5. Nuclear Radiation isotopes of atoms with unstable nuclei are called _______________________ these radioisotopes emit radiation to try & get a more stable atomic configuration while undergoing radioactive decay, atoms lose energy by emitting radiation three most common types of radiation are alpha (α), beta (β), & gamma (γ) 5

6. Nuclear Radiation Table 24.2 – Pg. 861 6

7. Nuclear Radiation Figure 24.2 – Pg. 862 7

8. Nuclear Radiation alpha particles (α) have same composition as helium atoms (2 protons & 2 neutrons) with a +2 charge ( ) Figure 24.3 – Pg. 862 8

9. Nuclear Radiation beta particles (β or e – ) are very fast moving electrons with a –1 charge ( ) – emitted when a neutron converts to a proton Figure 24.4 – Pg. 863 9

10. Nuclear Radiation gamma rays (γ) are high energy photons with no mass or charge ( ) – always accompanies other nuclear decays 10

11. Nuclear Radiation x–rays are a form of high-energy electromagnetic radiation – not produced by radioactive sources – emitted from certain materials in an excited state 11

12. Penetrating Power the more energy content of the radiation, the more damage it can cause different rays can penetrate different levels of the human body (α stopped by skin, β can penetrate 1cm, are highly penetrating) 12

13. Radioactive Decay all decay (except gamma radiation) involves the conversion of an element into another element ______________________________ – when an atom’s atomic number is altered protons & neutrons also called ___________________ nucleons held in the nucleus by the strong nuclear force 13

14. Radioactive Decay ________________________________________ – acts on subatomic particles that are extremely close together & it overcomes the electrostatic repulsion among protons Figure 24.6 – Pg. 865 14

15. Radioactive Decay atoms undergo radioactive decay to gain stability types of decay – ___________________________ ________________________________________ ________________________________________ 15

16. Radioactive Decay beta decay decreases the # of neutrons in an atom by converting it to a proton results in a new atom with no loss in the _______________________ & gain of 1 in _______________________ Figure 24.8a – Pg. 867 16

17. Radioactive Decay alpha decay decreases the # of neutrons & protons results in a new atom with a loss of 4 in the _______________________ & loss of 2 in _______________________ Figure 24.8b – Pg. 867 17

18. Radioactive Decay _______________________ – a decay process that involves the emission of a positron from the nucleus to reduce protons _______________________ – a particle with the same mass as an electron, but opposite charge results in a new atom with no loss in the _______________________ & loss of 1 in _______________________ Figure 24.9a – Pg. 868 18

19. Radioactive Decay _____________________ – occurs when the nucleus of an atom draws in a surrounding electron & combines it with a proton to form a neutron results in a decrease in protons results in a new atom with no loss in the _____________________ & loss of 1 in _____________________ Figure 24.9b – Pg. 868 19

20. Radioactive Decay Table 24.3 – Pg. 868 20

21. Radioactive Decay nuclear reactions are expressed by a balanced nuclear equation in nuclear equations mass numbers & charges are conserved – treat the arrow like an equal sign & make sure the mass numbers & atomic numbers equal on both sides of the equation 21

22. Radioactive Decay Examples: Write balanced nuclear equations for the following processes 1.carbon–11 produces a positron 2.bismuth–214 produces a β particle 3.neptunium–237 produces an α particle 4.Uranium-235 undergoes electron capture 5.silver–116 produces a β particle 6.bismuth–211 produces an α particle and 3 gamma rays 22

23. Radioactive Decay Examples: carbon–11 produces a positron _____________________________ 23

24. Radioactive Decay Examples : bismuth–214 produces a β particle _____________________________ 24

25. Radioactive Decay Examples : neptunium–237 produces an α particle _____________________________ 25

26. Radioactive Decay Examples : uranium–235 undergoes electron capture 26 _____________________________

27. Radioactive Decay Examples : silver–116 produces a β particle 27

28. Radioactive Decay 28 Examples : bismuth–211 produces an α particle and 3 gamma rays

29. Radioactive Decay Series many times a radioactive nucleus can not create a stable (nonradioactive) atom through a single decay ___________________________________________ – a series of nuclear reactions that begins with an unstable nucleus & results in the formation of a stable nucleus – most well known series is of uranium–238 to lead–206 (it takes 14 different radioactive decay steps) 29

30. Radioactive Decay Series Figure 24.10 – Pg. 870 30

31. Radioactive Decay Example : The first 4 steps of uranium–238 decaying into lead–206 are alpha, beta, beta, alpha. Write the nuclear equation for each step. 1.. 2.. 3.. 4.. 31

32. Radioactive Decay Rates to measure the speed (rate) of decays, scientists use half–lives ____________________________ – the amount of time required for ½ of a radioisotope to decay into its products 32

33. Radioactive Decay Rates every radioactive nuclide has a specific half-life from seconds to billions of years example: gold–198 (used for cancer treatment) has a half–life of 2.7 days – how much would remain of a 50g implant after 1 week? 33

34. Radioactive Decay Rates Example: the half–life of strontium–90 is 29 years; if you had 10.0 g of strontium–90 today, 29 years from now you would have 5.0 g left Table 24.4 – Pg. 871 34

35. Figure 24.11 – Pg. 871 35

36. Radioactive Decay Rates each radioisotope has a specific half–life – range from seconds to billions of years Table 24.5 – Pg. 871 36

37. Radioactive Decay Rates Example: Krypton-85 is used in indicator lights of appliances. The half-life of krypton-85 is 11 years. How much of a 2.000 mg sample remains after 33 years? 1 st look at what is known/unknown: – initial amount = 2.000 mgamount remaining = ? mg – elapsed time (t) = 33 years – half-life (T) = 11 years 2 nd solve for unknown 37

38. Radioactive Decay Rates 2 nd solve for unknown (cont.) – since there have been 3 half–lives, then divide initial amount by 2 three times 38

39. Radioactive Decay Rates Example: The half-life of cobalt-57 is 270 days. How much of a 5.000 mg sample will remain after 810 days? 39

40. Radioactive Decay Rates since half-lives are constant, radioisotopes can be used to determine the age of an object ________________________________________ – the process of determining the age of an object by measuring the amount of certain isotopes – carbon-14 (half-life = 5730 years) dating used to measure the age of artifacts that were once part of a living organism – other radioisotopes like uranium-238 (half-life = 4.5x10 9 years) to date older objects 40

41. Nuclear Reactions we’ve seen where one element can be converted into another through spontaneous emission of radiation (transmutation) elements can also be forced to transmutate by bombarding them with high-energy alpha, beta, or gamma radiation 41

42. Nuclear Reactions ________________________________________ – the process of striking nuclei with high-velocity charged particles – Rutherford did this in his experiment – particle accelerators use electrostatic & magnetic fields to accelerate charged particles at high speeds Figure 24.13– Pg. 875 42

43. Nuclear Reactions ________________________________________ – the elements with atomic numbers 93 & higher (right after uranium) all these elements were produced by induced transmutation they are also radioactive 43

44. Nuclear Energy to gain stability heavy nuclei can split into smaller nuclei ________________________________________ – the splitting of nuclei into fragments – fission comes with a very large release of energy – produces 26 million times as much energy as the an equal amount of natural gas 44

45. Nuclear Fission nuclear power plants use fission to produce electricity – by bombarding uranium-235 with neutrons 45

46. Nuclear Fission each fission of uranium-235 releases 2 neutrons these 2 neutrons can then cause another fission reaction – which then produces 2 more neutrons this self–sustaining process is called a ________________________________________ amount of energy released can increase rapidly – how atomic bombs work 46

47. Nuclear Fission Figure 24.16– Pg. 879 47

48. Nuclear Fission 48

49. Nuclear Fission if exactly one neutron causes another fission event then the process is said to be critical to get to critical state, a specific mass of fissionable material is used called the ____________________ Figure 24.17– Pg. 880 49

50. Nuclear Fission fission can be used to produce energy controlled reactions can occur in reactors energy produced is used to heat water to make steam to run generators 50

51. Nuclear Fission Figure 24.20– Pg. 881 51

52. Nuclear Fission inside the reactor core, neutrons are slowed down by a moderator and by _______________________ (made of substances that absorb neutrons – ex. Cd, B) nuclear reactors produce highly radioactive waste 52

53. Nuclear Energy can combine lighter elements (mass #s < 60) ________________________________________ – the combining of atomic nuclei the sun is powered by fusion reactions 53

54. Nuclear Fusion fusion seen as better than fission – products are not generally radioactive – produces much more energy – lighter elements are more abundant however fusion requires extremely high energy for reaction to go – also known as _________________________________ – ex. fusion of hydrogen atoms needs 5,000,000 K (8,999,540 °F) 54

55. 2 types of nuclear energy 1._______________ _ – combining 2 light nuclei to form a heavier nucleus 1._______________ _ – splitting a heavy nucleus into 2 nuclei with smaller mass #s Country (in order of total nuclear output) % of Total Power Production 1. United States20.2 2. France75.2 3. Japan28.9 4. Russia17.8 5. Germany26.1 6. South Korea31.1 7. Ukraine48.6 8. Canada14.8 9. United Kingdom17.9 10. China1.9 55

56. Nuclear Detection radiation with enough energy to ionize matter that it collides with is called ionizing radiation ______________________________________ uses this to detect radiation Figure 24.24– Pg. 885 56

57. Nuclear Detection also detected by _______________________________ – they detect bright flashes when ionizing radiation excites electrons of atoms Figure 24.25– Pg. 886 57

58. Medicinal Uses radioactive nuclides used to study how healthy areas of the human body are _____________________________ – radioactive nuclides that can be introduced into organisms and traced by monitoring their radioactivity used to detect diseases & monitor the effectiveness of a drug 58

59. Medicinal Uses radiation can damage or destroy healthy cells can also destroy unhealthy cells (cancer) radiation therapy also destroys healthy cells in the process of destroying cancerous cells (side effects) 59

60. Medicinal Uses 60 NuclideHalf-LifeArea of the Body Studied 131 I8.1 daysthyroid 59 Fe45.1 daysred blood cells 99 Mo67 hoursmetabolism 32 P14.3 dayseyes, liver, tumors 51 Cr27.8 daysred blood cells 87 Sr2.8 hoursbones 99 Tc6.0 hoursheart, bones, liver, lungs 133 Xe5.3 dayslungs 24 Na14.8 hourscirculatory system

61. Radiation Table 24.6 – Pg. 889 61

62. Radiation Table 24.7 – Pg. 889 62