Slides Shown Fri. Oct. 17 and Mon. Oct. 20

1. Slides Shown Fri. Oct. 17 and Mon. Oct. 20

2. Electromagnetic Radiation Has Oscillating Electric (E) and Magnetic (H) Fields in Planes Perpendicular to Each Other and to the Direction of Propagation.

3. The nature of waves

4. Figure 12.3: Classification of electromagnetic radiation

6. DISTRIBUTION OF STABLE NUCLIDES • Protons Neutrons Stable Nuclides % • Even Even 168 60.2 • Even Odd 57 20.4 • Odd Even 50 17.9 • Odd Odd 4 1.4 Total = 279 99.9%

7. PROPERTIES OF FUNDAMENTAL PARTICLES • Particle Symbol Charge Mass • (x10 -19 C) (x10-27kg) • Proton P +1.60218 1.672623 • Neutron N 0 1.674929 • Electron e -1.60218 0.0005486

8. NUCLEAR STABILITYModes of Radioactive Decay • Alpha Decay - Heavy Isotopes - 42He+2- • Beta Decay - Neutron Rich Isotopes - e -- • Positron Emission -Proton Rich Isotopes - • Electron Capture - Proton Rich Isotopes • x - rays • Gamma-ray emission( - Decay of nuclear • excited states • Spontaneous Fission - Very Heavy Isotopes

9. Comparison of Chemical and Nuclear Reactions Chemical Reactions Nuclear Reactions 1. One substance is converted to 1. Atoms of one element typically another,but atoms never change change into atoms of another. identity. 2. Orbital electrons are involved as 2. Protons, neutrons, and other bonds break and form; nuclear particles are involved; orbital particles do not take part. electrons take part. 3. Reactions are accompanied by 3.Reactions are accompanied by relatively small changes in energy relatively large changes in and no measurable changes in mass. energy and often measurable changes in mass. 4. Reaction rates are influenced by 4. Reaction rates are affected by temperature, concentration, number of nuclei, but not by catalysts, and the nature of the temperature, catalysts, or the chemical substance. nature of the chemical substance.

10. Emission and Absorption of Light by Atoms Light Light Nucleus of atom Electron Light Emission occurs when an electron drops from a higher energy level to a lower one. Light Absorption by an atom moves an electron to a higher energy level.

11. Absorption and Emission of Light by The Nucleus Excited state Ground state Protons and Neutrons in the nucleus are moved up to excited states by the absorption of large amounts of energy, and they move from excited states back to the ground states by the emission of large amounts of energy! This energy is normally 106 times larger than the energy emitted by electron transfers around atoms, and is in the Gamma ray region of the electromagnetic spectrum.

12. Gamma Ray Emission, the Nuclear Particles in the Nucleus dropping from excited states to their ground states. Example is the decay of cobalt – 60 to excited states in nickel – 60, which then decay to the ground state of 60Ni. Beta decay, e- 60Co 2.405 Mev 1.173 Mev Gamma ray 1.332 Mev 1.332 Mev Gamma ray Ground state of 60Ni

14. Table 20.4

15. Decay of a 10.0 -g sample of strontium-90 over time.

16. Change in the amount of Molybdenum - 99 with time

17. Schematic diagram of a cyclotron

18. CERN, the world's largest particle accelerator, lies at the foot of the Jura Mountains near Geneva, Switzerland.

19. Diagram of a linear accelerator

20. Accelerator tunnel at Fermilab, a high-energy particle accelerator in Batavia, Illinois. Source: Fermilab Batavia, IL

21. Table 20.4

22. Binding energy per nucleon as a function of mass number.

23. Units used for Nuclear Energy Calculations electron volt - (ev) The energy an electron acquires when it moves through a potential difference of one volt: 1 ev = 1.602 x 10-19J Binding energies are commonly expressed in units of megaelectron volts (Mev) 1 Mev = 106 ev = 1.602 x 10 -13J A particularly useful factor converts a given mass defect in atomic mass units to its energy equivalent in electron volts: 1 amu = 931.5 x 106 ev = 931.5 Mev

24. Binding Energy per Nucleon of Deuterium Deuterium has a mass of 2.01410178 amu. Hydrogen atom = 1 x 1.007825 amu = 1.007825 amu Neutrons = 1 x 1.008665 amu = 1.008665 amu 2.016490 amu Mass difference = Theoretical mass - actual mass = 2.016490 amu - 2.01410178 amu = 0.002388 amu Calculating the binding energy per nucleon: Binding Energy -0.002388 amu x 931.5 Mev / amu Nucleon 2 nucleons = - 1.1123 Mev / nucleon =

25. Calculation of the Binding Energy per Nucleon for Iron- 56 The mass of Iron -56 is 55.934939 amu, it contains 26 protons and 30 Neutrons Theoretical Mass of Fe - 56 : Hydrogen atom mass = 26 x 1.007825 amu = 26.203450 amu Neutron mass = 30 x 1.008665 amu = 30.259950 amu 56.463400 amu Mass defect =Actual mass - Theoretical mass: 55.934939 amu - 56.463400 amu = - 0.528461 amu Calculating the binding energy per nucleon: Binding Energy - 0.528461 amu x 931.5 Mev / amu nucleon 56 nucleons = = -8.7904 Mev / nucleon

26. Calculation of the Binding Energy per Nucleon for Uranium - 238 The actual mass of Uranium - 238 = 238.050785 amu, and it has 92 protons and 146 neutrons Theoretical mass of Uranium 238: Hydrogen atom mass = 92 x 1.007825 amu = 92.719900 amu neutron mass = 146 x 1.008665 amu = 147.265090 amu 239.98499 amu Mass defect = Actual mass - Theoretical mass: 238.050785 amu - 239.98499 amu = - 1.934205 amu Calculating the Binding Energy per nucleon: Binding Energy -1.934205 amu x 931.5 Mev / amu mucleon 238 nucleons = = - 7.5702 Mev / nucleon

27. Mass and Energy in Nuclear Decay - I Consider the alpha decay of 212Po T1/2 = 0.3 s 212Po 208Pb +  + Energy 211.988842 g/mol 207.976627 g/mol + 4.00151 g/mol Products = 207.976627 + 4.00151 = 211.97814 g/mol Mass = Po - Pb +  = 211.988842 211.97814 0.01070 g/mol E = mc2 = (1.070 x 10-5 kg/mol)(3.00 x 108m/s)2 = 9.63 x 1011 J/mol 9.63 x 1011 J/mol 6.022 x 1023 atoms/mol = 1.60 x 10-12J/atom

28. Mass and Energy in Nuclear Decay - II The Energy for the Decay of 212Po is 1.60 x 10-12J/atom 1.60 x 10-12J/atom 1.602 x 10-19 J/ev = 1.00 x 107 ev/atom 10.0 x 106 ev 1.0 x 10-6 Mev atom ev x = 10.0 Mev/atom !!!!! The decay energy of the alpha particle from 212Po is = 8.8 Mev !!!!