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Molecules PowerPoint Presentation

Molecules

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Molecules

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  1. Molecules E&R Chapter 12

  2. Outline • Bonding 12-1 • Ionic 12-2 • Covalent 12-3 • Molecular Excitations 12-4 • Rotation 12-5 • Vibration 12-6 • Electronic • Electronic + Vibration + Rotation 12-7

  3. Bonding http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/chemcon.html#c1 R Nave, Georgia State Univ

  4. Chemical Bonding http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bondcon.html#c1 R Nave, Georgia State Univ

  5. Ionic Bonds RNave, GSU at http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html#c4

  6. Ionic Bonds

  7. Ionic Bonding RNave, Georgia State Univ at hyperphysics.phy-astr.gsu.edu/hbase/molecule

  8. Ionic Bonding a.u. = atomic energy unit = 2*(13.6eV) Brandsen&Joachim

  9. E&R

  10. Covalent Bonds RNave, GSU at http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html#c4

  11. Covalent Bonding SYM ASYM spatial spin ASYM SYM spatial spin

  12. Covalent Bonding not really parallel, but spin-symmetric Stot = 1 Stot = 0 not really anti, but spin-asym

  13. Covalent Bonding Bransden&Joachin

  14. Ionic Characteristics Crystalline solids High melting & boiling point Conduct electricity when melted Many soluble in water, but not in non-polar liquids Covalent Characteristics Gases, liquids, non-crystalline solids Low melting & boiling point Poor conductors in all phases Many soluble in non-polar liquids but not water Ionic vs Covalent Bond Properties

  15. Rotational Spectra w rotational A.M. moment of inertia

  16. Rotation

  17. Rotation

  18. Rotational Spectra

  19. Ocean Optics: Nitrogen N2 ~ 0.3 eV ~ 0.4 eV

  20. Vibration

  21. Vibration (in an Electronic state)

  22. Electronic + Vibration

  23. Electronic + Vibration + Rotation 2.550 eV 2.656 eV electronic excitation gap vibrational excitation gaps

  24. Electronic + Vibration + Rotation Vibrational Well Vibrational Well 2.656 eV depth ~ 0.063 eV electronic excitation gap vibrational excitation gaps

  25. Electronic, Vibration, Rotation Electronic ~ optical & UV ~ 1 – 3 eV Vibration ~ IR ~ 10ths of eV Rotation ~ microwave ~ 1000ths of eV

  26. Electronic + Vibration + Rotation 2.550 eV 2.656 eV electronic excitation gap vibrational excitation gaps

  27. ** + Vibration + Rotation IN A DIATOMIC MOLECULE because a photon has one unit of angular momentum, the rotational quantum number must change (vib is not angular motion) Dr = 0 not allowed

  28. ** + Vibration + Rotation

  29. Ocean Optics: Nitrogen N2 ~ 0.3 eV ~ 0.4 eV

  30. Some Molecular Constants Notes: a) vibrational frequency in table is given as f / c b) moment of inertia in table is given as hbar2/(2I) / hc

  31. Fluorescence absorb at one wavelength, emit at another

  32. Phosphorescence tunneling slows the decay process