1 / 28

Understanding Hybridization in Molecular Orbitals

Explore the concept of hybridization and molecular orbitals to comprehend molecular geometry and bonding. Learn how different hybridizations like sp3, sp2, and sp enhance our understanding of bond formations in molecules.

warddavid
Download Presentation

Understanding Hybridization in Molecular Orbitals

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 10 Hybridization and Molecular Orbitals

  2. Atomic Orbitals Don’t Work • to explain some molecular geometry. • In methane, CH4, the shape s tetrahedral. • The valence electrons of carbon should be two in s, and two in p. • the p orbitals would have to be at right angles. • The atomic orbitals change when making a molecule

  3. Hybridization • We blend the s and p orbitals of the valence electrons and end up with the tetrahedral geometry. • We combine one s orbital and 3 p orbitals. • sp3hybridization has tetrahedral geometry.

  4. sp3 In terms of energy 2p Hybridization Energy 2s

  5. How we get to hybridization • We know the geometry from experiment. • We know the orbitals of the atom. • hybridizing atomic orbitals can explain the geometry. • So if the geometry requires a tetrahedral shape, it is sp3 hybridized. • If the molecule has four single bonds, it is sp3 hybridized. • This includes bent and trigonal pyramidal molecules because one of the sp3 lobes holds the lone pair.

  6. sp2 hybridization • C2H4 • Double bond acts as one pair. • trigonal planar • Have to end up with three blended orbitals. • Use one s and two p orbitals to make sp2 orbitals. • Leaves one p orbital perpendicular.

  7. 2p sp2 Hybridization In terms of energy 2p Energy 2s

  8. Where is the P orbital? • Perpendicular • The overlap of orbitals makes a sigma bond (s bond)

  9. Two types of Bonds • Sigma bonds from overlap of orbitals. • Between the atoms. • Pi bond (p bond) above and below atoms • Between adjacent p orbitals. • The two bonds of a double bond.

  10. H H ∏ C C H H

  11. sp2 hybridization • When three things come off atom. • trigonal planar • 120º • on s one p bond

  12. What about two • When two things come off. • One s and one p hybridize. • linear

  13. sp hybridization • End up with two lobes 180º apart. • p orbitals are at right angles • Makes room for two p bonds and two sigma bonds. • A triple bond or two double bonds.

  14. 2p sp Hybridization In terms of energy 2p Energy 2s

  15. CO2 • C can make two s and two p • O can make one s and one p O C O

  16. Breaking the octet • PCl5 • The model predicts that we must use the d orbitals. • dsp3 hybridization • There is some controversy about how involved the d orbitals are.

  17. dsp3 • Trigonal bipyrimidal • can only s bond. • can’t p bond. • basic shape for five things.

  18. PCl5 Can’t tell the hybridization of Cl Assume sp3 to minimize repulsion of electron pairs.

  19. d2sp3 • gets us to six things around • octahedral

  20. Molecular Orbital Model • Localized Model we have learned explains much about bonding. • It doesn’t deal well with the ideal of resonance, unpaired electrons, and bond energy. • The MO model is a parallel of the atomic orbital, using quantum mechanics. • Each MO can hold two electrons with opposite spins • Square of wave function tells probability

  21. What do you get? • Solve the equations for H2 • HA HB • get two orbitals • MO1 = 1sA - 1sB • MO2 = 1sA + 1sB

  22. The Molecular Orbital Model • The molecular orbitals are centered on a line through the nuclei • MO1 the greatest probability is between the nuclei • MO2 it is on either side of the nuclei • this shape is called a sigma molecular orbital

  23. The Molecular Orbital Model • In the molecule only the molecular orbitals exist, the atomic orbitals are gone • MO1 is lower in energy than the 1s orbitals they came from. • This favors molecule formation • Called an bonding orbital MO2 is higher in energy • This goes against bonding • antibonding orbital

  24. The Molecular Orbital Model MO2 Energy 1s 1s MO1

  25. The Molecular Orbital Model • We use labels to indicate shapes, and whether the MO’s are bonding or antibonding. • MO1 = s1s • MO2 = s1s* (* indicates antibonding) • Can write them the same way as atomic orbitals • H2 = s1s2

  26. The Molecular Orbital Model • Each MO can hold two electrons, but they must have opposite spins • Orbitals are conserved. The number of molecular orbitals must equal the number atomic orbitals that are used to make them.

  27. H2- s1s* Energy 1s 1s s1s

  28. Bond Order • The difference between the number of bonding electrons and the number of antibonding electrons divided by two

More Related