1. Nuclear ChemistryP Squires Basic Chemistry 2005-2006

2. Isotopes have the same number ofprotons and electrons butdifferent numbers ofneutrons. 3. Isotopes have different mass numbers but the same atomic number. 4. Symbols for Isotopes Mass number Symbol U235 92of ElementAtomicnumber 5. Symbols for IsotopesMass numberA is the A Symbol Esymbol formass ofnumber Z Element Z is the symbol forAtomic atomic numbernumber 6. IsotopesConsider an atom of aluminum with 13 protons and 15 neutrons. What is Z and A?A = #p + #n+13 + 15 = 28 7. How are isotopes of the same element alike and different?Alike: Different:1. Number of 1. Number of protons andneutrons electrons2. Atomic number 2. Mass Number3. Chemical3. Atomic weight of properties the isotopes 8. Isotopes See IllustratedIsotope example 9. Finding the number of Protons,Neutrons, and ElectronsThe atomic number is the number of protons in the nucleus.The number of electrons in a neutral atom equals the number of protons. 10. Finding the number of Protons,Neutrons, and Electrons# of neutrons = A - Z 11. Finding the number of Protons, Neutrons, and ElectronsZ = 92 U-235protons = 92electrons = 92A = 235protons + neutrons = 235 12. Finding the number of Protons, Neutrons, and ElectronsQ. Find the number of neutrons in the Ba-137 isotope. 13. Finding the number of Protons, Neutrons, and ElectronsElement Symbol Z A#p #n #e Zinc66 In6885 3882 210 Rn13635 47 14. Finding the number of Protons, Neutrons, and ElectronsElement Symbol Z A #p #n #e ZincZn 30 66 30 36 30 In 68853882 210 Rn 136 35 47 15. Finding the number of Protons, Neutrons, and ElectronsElement Symbol Z A #p #n #e ZincZn 30 66 30 36 30Indium In 49 117 49 68 49853882 210 Rn 136 35 47 16. Finding the number of Protons, Neutrons, and ElectronsElement Symbol ZA #p #n #eZincZn 3066 30 36 30 Indium In 49 117 49 68 49Strontium Sr 3885 38 47 38 82 210Rn 13635 47 17. Finding the number of Protons, Neutrons, and ElectronsElement Symbol ZA #p #n #eZincZn 30 66 30 36 30 Indium49 117 49 68 49Strontium Sr 38 85 38 47 38LeadPb 82 210 82 128 82Rn 136 18. Finding the number of Protons, Neutrons, and ElectronsElement Symbol ZA #p #n #eZincZn 3066 30 3630 Indium In 49 117 49 6849Strontium Sr 3885 38 4738LeadPb 82 210 82 128 82 RadonRn 86 222 86 136 8635 47 19. Finding the number of Protons, Neutrons, and ElectronsElement Symbol ZA #p #n #eZincZn 3066 30 3630 Indium In 49 117 49 6849Strontium Sr 3885 38 4738LeadPb 82 210 82 128 82 RadonRn 86 222 86 136 86Bromine Br 3582 35 4735 20. Only one element has uniquenames for its isotopes 11 H = hydrogen21 H = deuterium31 H = tritiumDeuterium and tritium are used innuclear reactors and fusion research. 21. Some isotopes are radioactive Radioactive isotopes are calledradioisotopes. Radioisotopes can emit alpha, betaor gamma radiation as they decay. Radioisotopes are important in anumber of research fields. 22. Protection from radiation1. Shielding2. Distance 23. Protection from radiation How do you protect yourself from Alpha 2.5 cm of air, paper, skinaluminum, lead, otherBetametals, wood, plastic, etc.Gammaup to a foot or two of lead, many feet of concrete 24. Properties of Alpha Particles Alpha () particles arethe nuclei of heliumatoms and have thesymbol 2He4 25. Properties of Beta ParticlesBeta () particles are high speed electrons ejected from the nuclei of atoms and have the symbol -1e .0 26. Properties of Gamma Rays Gamma () rays are high energyelectromagnetic waves, notparticles. Gamma rays have shortwavelengths and high energiesand travel at the speed of light. 27. Alpha, Beta, GammaElectrically charged plates+ + + + + + + + What is the effect of electricallycharged plates on , , ?- - - - - - - - -Radioactive Source 28. Alpha, Beta, GammaElectrically charged plates+ + + + + + + + - - - - - - - - - Radioactive Source 29. Alpha, Beta, Gamma Why do the , and rays take the paths that they do? 30. Alpha, Beta, GammaPaperLeadAluminumRadioactivefoilSource 31. Alpha, Beta, GammaPaperLead AluminumRadioactivefoilSource 32. Alpha, Beta, GammaPaperLead AluminumRadioactivefoilSource 33. Decayequations 34. Alpha DecayIn alpha decay, an alpha particle (2He4) is released from the nucleus. 35. Alpha decay decay product92 U 238 2He + 90Th 4234 alpha particle 36. Alpha decayRadon-220 decays by alpha emission.What is the decay product?86 Rn 220 2He +484 Po ???216 37. Alpha decayWrite the alpha decay equations for:1. 95Am 2412He + 93Np 42372. 84Po216 2He + 82Pb 4 2123. 88Ra226 2He + 86Rn 4 222 38. Beta DecayBeta decay occurs because of the instability of a neutron.Neutrons are a little more massive than protons; and neutrons are neutral. 39. Beta decayDecay of a neutron: 0n1 1H1 + -1e0 neutron protonelectronThe electron ejected from thenucleus is a beta particle. 40. Start with a Li atom with Beta decay3 protons andSuddenly a 4 neutrons.neutrondecays!Now there A beta particleare 4 protons goes zipping out ofand 3 neutrons.the nucleus. 41. Beta decay decay product6 C 14 7N 14+ -1e 0 beta particle 42. Beta decayZn-62 decays by beta emission.What is the decay product?30 Zn -1e + 62 0??? 31Ga 62 43. Beta decayWrite the beta decay equations for:1. 82Pb214 -1 e + 83Bi02142. 27Co 62 -1 e + 28Ni0623. 47??? Ag 113 -1 e + 48Cd 0 113 44. Gamma DecayGamma rays are neutraland thus no change ismade in the equation. 6 C 14 6C 14+ 45. Half life 46. What is half life?Half life is the time needed for one half of a radioisotope to decay. 47. Half Life Take 100 pennies and throw them on thefloor. Remove those that are heads up. Count remaining pennies. Continue until only one penny remains. What can this tell us about Half Life? 48. What is half life? Suppose you start with 100.0 grams of a radioisotope that has a half life of exactly 1 year.How much will be left after 1 year?How much will be left after 2 years? 49. Half life projectQuestions:1. A radioisotope has a half-life of 100years. How long will it take for theradiation to decrease to 1/16 of itsoriginal value?400 years 50. Half life projectQuestions:2. A radioisotope has an activity of 560 counts perminute. After 16 hours the count rate has droppedto 35 counts per minute. What is the half life ofthe radioisotope? 4 hours 51. Nuclear Fission 52. Nuclear fissionFission the splitting of an atom after being struck by a neutron. 53. Nuclear Fission 54. Nuclear fission Fission fragment U-235U-235 NeutronsNeutronFission fragment U-235 55. Nuclear fissionTo picture a chain reaction, imagine50 mousetraps in a wire cage. And on each mousetrap are two ping-pong balls.Now imagine dropping one moreping-pong ball into the cage 56. Detail ofping-pongballs onmousetraps.http://www.physics.montana.edu/demonstrations/video/modern/demos/mousetrapchainreaction.html 57. http://www.physics.montana.edu/demonstrations/video/modern/demos/mousetrapchainreaction.html 58. http://www.physics.montana.edu/demonstrations/video/modern/demos/mousetrapchainreaction.html 59. Nuclear fission This heat energy can be harnessedto boil water,creating steam,that can turn a generator,creating electricity. 60. Nuclear Fusion 61. Nuclear fusion A daywithout sunshine is aday withoutfusion. 62. Nuclear Fusion 63. How do we detectradiation? 64. Geiger-Mueller Tube Counter2435Wire (+ side of circuit) Metal shield (- side)Low pressure Ar gasMica window (fragile) 65. GM Tube Rays leave the source Some hit the GM tube Most do nothing One ray may cause a dischargeSource and the detector clicks 66. GM TubeFilled with low pressure argon gasAbout 1% efficiencyAbout 1 in 100 rays causes an electric spark between the case and the wire Each spark registers as a count or click on the counter 67. Nuclear Fuel Cycle 68. Nuclear Fuel Cycle The Nuclear Fuel Cycle consists ofsequence of steps in which uranium ore ismined, milled, enriched, and fabricated intonuclear fuel and then irradiated in a reactorfor several years. The entire fuel cycle lifetime from miningto discharge is about 8 years. 69. Where is Nuclear Waste Kept? After irradiation the fuel is cooled in thespent fuel pit for several years and thenmoved to dry cask storage on the reactorsite. 70. Spent Nuclear Fuel Pool Keep spent fuel rods under at least 20 feet of water to provide adequate shielding from the radiation for anyone near the pool Spent Fuel Pools were designed as TEMPORARY storage for fuel while short lived isotopes decay (