Chemical Bonding II: Molecular Geometry and Hybridization of Atomic Orbitals

1. Chemical Bonding II:Molecular Geometry and Hybridization of Atomic Orbitals Chapter 10

2. Bonding: Orbitals Chapter 10 Topics • Valence Bond Theory & Molecular Geometry • Dipole moments • Hybridization • Sigma and pi bond

3. Cl H F Cl Cl F F Cl P C C H S Cl O O B H F F Cl Cl Cl H F .. F F .. F F O S .. .. Br .. Cl F F F N O F H H H .. .. F F F .. .. .. Xe O S F F F H F F H I .. .. .. I I • VPT Theory and shape of molecules (Electron groups want to be as far as possible from each other) 2 groups of valnece e- 3 groups of valnece e- 4 groups of valnece e- 5 groups of valnece e- 6 groups of valnece e- MX6 MX2 MX3 MX4 MX5 Octahedral Trigonal Bipyramidal Linear Planar Triangular Tetrahedral MX4E MX3E MX2E MX5E Unsymmetrical Or distorted tetrahedron Trigonal Pyramidal Square Pyramidal V-Shaped Nonlinear bent MX2E2 MX4E2 MX3E2 Nonlinear Bent V-shaped Planar Square T-Shaped MX2E3 Linear

4. 0 lone pairs on central atom Cl Be Cl 2 atoms bonded to central atom

8. Cl H F Cl Cl F F Cl P C C H S Cl O O B H F F Cl Cl Cl H F .. F F .. F F O S .. .. Br .. Cl F F F N O F H H H .. .. F F F .. .. .. Xe O S F F F H F F H I .. .. .. I I • Dipole moments and polar molecule 2 groups of valnece e- 3 groups of valnece e- 4 groups of valnece e- 5 groups of valnece e- 6 groups of valnece e- Not P No D Not P No D Not P No D Not P No D MX6 MX2 MX3 MX4 MX5 Octahedral Trigonal Bipyramidal Linear Planar Triangular Tetrahedral P D P D P D Not Polar No Dipole Moment MX4E MX3E MX5E Unsymmetrical Or distorted tetrahedron Trigonal Pyramidal Square Pyramidal P D P D P D Not P No D MX2E2 MX4E2 MX2E MX3E2 Nonlinear Bent V-shaped Planar Square T-Shaped V-Shaped Nonlinear bent Not P No D MX2E3 Linear

9. F F F F Xe F F O F F F Cl Br H H F F F square planar bent square pyramidal T-shaped

11. F S F F O O S F Q) What are the molecular geometries of SO2 and SF4? AB4E AB2E distorted tetrahedron bent

12. Sa. Ex. 8.12: Predict the geometry of PCl5, PCl4+, PCl6- Sa. Ex. 8.13: Predict the geometry of XeF4

13. O O S H H H O O O C H H C H Q) Which of the following molecules have a dipole moment? H2O, CO2, SO2, and CH4 dipole moment polar molecule dipole moment polar molecule no dipole moment nonpolar molecule no dipole moment nonpolar molecule

14. Q) Does CH2Cl2 have a dipole moment?

15. Hybridization For NH3 N – 1s22s22p3 3 H – 1s1 Q) If the bonds form from overlap of 3 2p orbitals on nitrogen with the 1s orbital on each hydrogen atom, what would the molecular geometry of NH3 be? If use the 3 2p orbitals predict 900 Actual H-N-H bond angle is 107.30

16. Hybridization – mixing of two or more atomic orbitals to form a new set of hybrid orbitals. • Mix at least 2 nonequivalent atomic orbitals (e.g. s and p). Hybrid orbitals have very different shape from original atomic orbitals. • Number of hybrid orbitals is equal to number of pure atomic orbitals used in the hybridization process. • Covalent bonds are formed by: • Overlap of hybrid orbitals with atomic orbitals • Overlap of hybrid orbitals with other hybrid orbitals

17. Q) How do I predict the hybridization of the central atom? Count the number of group of electrons Number of group of electrons Hybridization Examples 2 sp BeCl2 3 sp2 BF3 4 sp3 CH4, NH3, H2O 5 sp3d PCl5 6 sp3d2 SF6

18. SP

19. SP2

20. SP3

24. Sigma and pi bond

25. H H C H C O O H Sigma (s) and Pi Bonds (p) 1 sigma bond Single bond 1 sigma bond and 1 pi bond Double bond Triple bond 1 sigma bond and 2 pi bonds Q) How many s and p bonds are in the acetic acid (vinegar) molecule CH3COOH? s bonds = 6 + 1 = 7 p bonds = 1

34. 10.5