1. Nuclear Reactions

2. Natural Transmutation 1 term on reactant side 1 term on reactant side Original isotope Original isotope 2 terms on product side 2 terms on product side Emitted Particle Emitted Particle New Isotope New Isotope Happens all by itself (spontaneous) Not affected by anything in environment

3. Natural Transmutation 16 N  0 e + 16 O 7 8 1 term on reactant side 2 terms on product side

4. Artificial Transmutation cause to happen: smash particles cause to happen: smash particles into one another into one another 2 terms on reactant side 2 terms on reactant side Original Isotope Original Isotope Particle that hits it Particle that hits it neutron, proton, or  -particleneutron, proton, or  -particle Product side: usually 2 terms Product side: usually 2 terms

5. Artificial Transmutation 27 Al + 4 He  30 P + 1 n 132 15 0 original isotope or target nucleus “bullet” -what hits isotope

6. Artificial Transmutation 27 Al + 4 He  30 P + 1 n 13 2150 14 N + 4 He  17 O + 1 H 7 28 1 75 As + 4 He  78 Br + 1 n 33 2350 37 Cl + 1 n  38 Cl 17 0 17 all these equations have 2 reactants!

7. Bombarding with protons or  protons &  -particles have positive charge and mass protons &  -particles have positive charge and mass do some damage when hit target nucleusdo some damage when hit target nucleus must be accelerated to high speeds to overcome repulsive forces between nucleus & particle (both are +)must be accelerated to high speeds to overcome repulsive forces between nucleus & particle (both are +)

8. What is an accelerator? vacuum chamber (usually long pipe) vacuum chamber (usually long pipe) surrounded by vacuum pumps, magnets, radio- frequency cavities, high voltage instruments & electronic circuitssurrounded by vacuum pumps, magnets, radio- frequency cavities, high voltage instruments & electronic circuits inside pipe particles are accelerated to very high speeds then smashed into each other inside pipe particles are accelerated to very high speeds then smashed into each other

9. Fission Reaction s plitting heavy nucleus into 2 lighter nuclei s plitting heavy nucleus into 2 lighter nuclei requires critical mass of fissionable isotope controlled: nuclear reactor controlled: nuclear reactor uncontrolled: bomb uncontrolled: bomb

10. Fission  reactant side: 2 terms 1 heavy isotope (examples: U-235 or Pu-239) 1 heavy isotope (examples: U-235 or Pu-239) bombarding particle – usually a neutron bombarding particle – usually a neutron product side: at least 2 terms product side: at least 2 terms 2 medium-weight isotopes 2 medium-weight isotopes 1 or more neutrons 1 or more neutrons huge amount energy released huge amount energy released Fission = Division Fission = Division

11. Fission Chain Reaction

12. Fission 235 U + 1 n  91 Kr + 142 Ba + 3 1 n + energy 92036 560 235 U + 1 n  72 Zn + 160 Sm + 4 1 n + energy 92030062 more than 200 different product isotopes identified from fission of U-235 small amount of mass is converted to energy according to E = mc 2

13. Fusion reactant side has 2 small nuclei: reactant side has 2 small nuclei: H + H; H + He; He + HeH + H; H + He; He + He product side: product side: 1 nucleus (slightly larger; still small) and maybe a particle1 nucleus (slightly larger; still small) and maybe a particle source of sun’s energy source of sun’s energy 2 nuclei unite 2 nuclei unite 2 H + 3 H  4 He + 1 n + energy 2 H + 3 H  4 He + 1 n + energy 1 1 2 0

14. CERN particles travel just below speed of light 10 hrs: particles make 400 million revolutions of ring 27 kilometer ring

15. FermiLab 4 miles in circumference!

17. Balancing Nuclear Equations

18. Nuclear Equations - tasks identify type (4 types) identify type (4 types) balance to find unknown term balance to find unknown term

19. Natural Transmutation – ID 1 term on reactant side 1 term on reactant side starting isotope starting isotope 2 terms on product side 2 terms on product side ending isotope & emitted particleending isotope & emitted particle type of particle emitted characteristic type of particle emitted characteristic of isotope – Table N of isotope – Table N

20. Nuclear Equations to balance: use conservation of both atomic number & mass number to balance: use conservation of both atomic number & mass number mass number = left superscriptmass number = left superscript atomic number = left subscriptatomic number = left subscript

21. Balancing Nuclear Equations 16 N  0 e + 16 O 7 8 conservation of mass number: 16 = 0 + 16 conservation of atomic number: 7 = -1 + 8

22. Writing Equations write equation for decay of Thorium-232 write equation for decay of Thorium-232 use Table N to find decay mode: α use Table N to find decay mode: α write initial equation: write initial equation: 232 Th  4 He + X 232 Th  4 He + X figure out what element it turned into figure out what element it turned into 902

23. What’s under the hat? Little cats X, Y, & Z!

24. Write an equation for the α decay of Th-232 232 Th  4 He + Y X what’s X? 952Z

25. 232 Th  4 He + X 902 conservation of mass number: sum mass numbers on left side must = sum mass numbers on right side = sum mass numbers on right sideY Z 232 = 4 + Y so Y = 228

26. 232 Th  4 He + 228 X 90 2 conservation of atomic number: sum of atomic numbers on left side must = sum of atomic numbers on right side = sum of atomic numbers on right sideZ 90 = 2 + Z so Z = 88

27. 232 Th  4 He + 228 X 90288 use PT to find X: X = Ra 232 Th  4 He + 228 Ra 90 2 88

28. Alpha (α) decay: 233 U  233 U  229 Th + 4 He 92 90 2 232 Th  232 Th  228 Ra + 4 He 90 88 2 90 88 2 175 Pt  175 Pt  171 Os + 4 He 78 76 2

29. How does the mass number or atomic number change in α,β or γ decay? go to Table N: go to Table N: find isotope that decays by α or β decayfind isotope that decays by α or β decay write equationwrite equation see how mass number (or atomic number) changessee how mass number (or atomic number) changes 226 88 Ra  4 2  + X so X has to be 222 86 X 226 88 Ra  4 2  + X so X has to be 222 86 X α decay of Ra-226: α decay of Ra-226: mass number decreases by 4mass number decreases by 4 atomic number decreases by 2atomic number decreases by 2

30. Radioactive Decay Series sometimes 1 transmutation isn’t enough to achieve stability sometimes 1 transmutation isn’t enough to achieve stability some radioisotopes go through several changes before achieve stability (no longer radioactive) some radioisotopes go through several changes before achieve stability (no longer radioactive)

32. β- 14 C  14 N + 0 e β+ 18 F  18 O + 0 e 67 8 +1 9 beta positron

33. How does the mass number or atomic number change in  or  decay? go to Table N; find isotope that decays by α,  or  ; write equation; see how mass number (or atomic number) changes go to Table N; find isotope that decays by α,  or  ; write equation; see how mass number (or atomic number) changes 226 Ra  4  + X so X has to be 222 X 226 Ra  4  + X so X has to be 222 X X is Ra-222 X is Ra-222 mass number decreases by 4mass number decreases by 4 atomic number decreases by 2atomic number decreases by 288286

35. Element (atom) UNSTABLESTABLE n/p ratio>1.5:11:1 up to 1.5:1 atomic number83 and above≤ 82 radioactiveYesNot So how do you know if an element is radioactive or not? the key is the proton to neutron ratio