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MO diagram for homonuclear diatomic molecules Li 2 through N 2

MO diagram for homonuclear diatomic molecules Li 2 through N 2. MO diagram for homonuclear diatomic molecules O 2 and F 2. N 2 Lewis diagram :N  N: each atom supplies 5 electrons; a total of 10 electrons must be assigned N 2 : s 2s 2 s * 2s 2 p 2p 4 s 2p 2 Bond order for N 2

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MO diagram for homonuclear diatomic molecules Li 2 through N 2

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  1. MO diagram for homonuclear diatomic molecules Li2 through N2 MO diagram for homonuclear diatomic molecules O2 and F2

  2. N2 Lewis diagram :NN: each atom supplies 5 electrons; a total of 10 electrons must be assigned N2: s2s2s*2s2p2p4s2p2 Bond order for N2 = 0.5 (8 - 2) = 3

  3. Lewis model O2 Molecular Orbital Theory O2: s2s2s*2s2s2p2 p2p4 p*2p1 p*2p1 Unpaired electrons - paramagnetic Bond order = 2 Agrees with Lewis diagram

  4. Heteronuclear diatomics - electrons are unequally shared by the two atoms due to electronegativity differences. y = cAyA + cByB Where cA and cB are coefficients which indicate the contribution of each AO in the MO In a homonuclear molecule: cA = cB = 1

  5. MO energy-level diagram for a AB type molecule. A is more electronegative than B Energy levels of the more electronegative element is lower than the less electronegative element s: higher contribution from A2s s*: higher contribution from B2s

  6. Lowest unoccupied MO (LUMO) Highest occupied MO (HOMO) CO - ten valence electrons CO: s2s2s*2s2p2p4 s2p2 Bond order = 0.5 (8 - 2) = 3

  7. Polyatomics - same principles as diatomics except that the MOs spread all over the atoms in the molecule An electron pair helps to bind the whole molecule, not just a pair of atoms. H2O: six atomic orbitals (one O2s, three O2p, and two H1s) These six orbitals are used to build six molecular orbitals in which the degree of net bonding characters is related to the number of internuclear nodes.

  8. Molecular Orbitals of H2O

  9. http://www.whfreeman.com/chemicalprinciples/con_index.htm?03 http://www.shef.ac.uk/chemistry/orbitron/

  10. Spectroscopy Spectroscopy: interaction of light with matter Average Bond energies (kJ/mol) C-H: 413 C=C: 610 H-F: 565 H-H: 436 CC: 835

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