1. Nuclear Decay October 15 nd & 16 th , 2009

3. X A Z Mass number Atomic number Element symbol = number of protons + number of neutrons = number of protons Isotope Symbol Review A = number of protons + number of neutrons Z = number of protons A – Z = number of neutrons **Number of neutrons = Mass Number – Atomic Number**

4. Fill in the chart for each isotope 235 92 92 143 92 92 238 146 Isotopes of any particular element contain the same number of protons, but different numbers of neutrons. U 235 92 U 238 92 A Z Number of protons Number of neutrons A Z Number of protons Number of neutrons

7. An alpha particle is identical to that of a helium nucleus. It contains two protons and two neutrons. Alpha Decay unstable atom more stable atom alpha particle X A Z Y A - 4 Z - 2 + He 4 2

8. Alpha Decay + Loss of 2 protons & 2 neutrons: Atomic # decreases by 2 Mass # decreases by 4 Ra 226 88 Rn 222 86 He 4 2

9. Write your own Alpha Decay What is Y? X A Z Y A - 4 Z - 2 + He 4 2 Rn 222 86 + Y A Z He 4 2 Rn 222 86 He 4 2 + Po 218 84 He 4 2

10. Write the equation for the alpha decay of Uranium-234 U 234 + He 4 2 U 234 92 + Th 230 90 He 4 2

11. Find the missing starting material X A Z + Pb 214 82 He 4 2 He 4 2 + Pb 214 82 He 4 2 Po 218 84

12. Beta Emission A beta particle is a fast moving electron which is emitted from the nucleus of an atom undergoing radioactive decay. Beta emission occurs when a neutron changes into a proton and an electron . b eta particle (electron) proton stays in nucleus X A Z Y A Z + 1 + e 0 -1

14. Write your own Beta Emission What is Y? X A Z Y A Z + 1 + e 0 -1 Th 234 90 Y A Z + e 0 -1 Th 234 90 Pa 234 91 + e 0 -1

15. Write the equation for the beta e mission of carbon-14 C 14 + C 14 N 14 7 + e 0 -1

16. Find the missing starting material X A Z Bi 214 83 + e 0 -1 Pb 214 82 Bi 214 83 + e 0 -1

17. Electron Capture is the opposite of Beta Emission Electron Capture The capture of the electron allows a proton to turn into a neutron X A Z e 0 -1 + Y A Z-1

19. Write your own Electron Capture What is Y? X A Z e 0 -1 + Y A Z-1 Ar 37 18 e 0 -1 + Y A Z-1 Ar 37 18 e 0 -1 + Cl 37 17

20. Write the equation for electron c apture of nickel-59 Ni 59 + Ni 59 28 e 0 -1 + Co 59 27

21. Find the missing starting material X A Z e 0 -1 + C 14 6 N 14 7 e 0 -1 + C 14 6

22. Positron Emission A positron is like an electron but it has a positive charge. During positron emission a proton changes into a neutron and the excess positive charge is emitted . positron mass stays in nucleus X A Z Y A Z - 1 + e 0 +1

24. Write your own Positron Emission What is Y? X A Z Y A Z - 1 + e 0 +1 B 8 5 Y A Z + e 0 +1 B 8 5 Be 8 4 + e 0 +1

25. Write the equation for the positron e mission of oxygen-16 O 16 + O 16 N 16 7 + e 0 +1

26. Find the missing starting material X A Z Cu 66 29 + e 0 +1 Zn 66 30 Cu 66 29 + e 0 +1

28. Summary Reaction What happens? Mass # Atomic # Alpha Decay  Lose Helium Nucleus -4 -2 Beta Decay  - Lose electron from nucleus (neutron turns into proton) No change +1 Electron Capture Gain electron in nucleus (proton turns into neutron) No change -1 Positron Emission   Lose positron (proton turns into neutron) No change -1 Gammy Decay  Emit high energy gamma ray No change No change

30. Nuclear Stability Graph Dark band = stable nucleus Areas off line = radioactive

34. Fission Fusion Nuclei combine Nucleus splits End product is heavier than reactants End product is lighter than reactants Energy is released LOTS of energy released Can’t contain reaction Reaction can be harnessed Nuclear Change