The document discusses molecular geometry and hybridization of atomic orbitals. It explains that the valence shell electron pair repulsion (VSEPR) model is used to predict molecular geometry based on electron pair repulsions. Molecular geometry is determined by the number of atoms bonded to the central atom and any lone pairs. Hybridization, such as sp, sp2, and sp3, is used to explain bonding based on the number of electron pairs around the central atom. Sigma and pi bonds are discussed, along with how hybridization relates to molecular geometry.

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

2. 10.1

3. Valence shell electron pair repulsion (VSEPR) model: Predict the geometry of the molecule from the electrostatic repulsions between the electron (bonding and nonbonding) pairs. AB 2 2 0 10.1 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry linear linear B B

4. 10.1 Cl Cl Be 2 atoms bonded to central atom 0 lone pairs on central atom

5. AB 2 2 0 linear linear VSEPR AB 3 3 0 10.1 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry trigonal planar trigonal planar

6. 10.1

7. AB 2 2 0 linear linear VSEPR 10.1 AB 4 4 0 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry AB 3 3 0 trigonal planar trigonal planar tetrahedral tetrahedral

8. 10.1

9. AB 2 2 0 linear linear VSEPR 10.1 AB 4 4 0 tetrahedral tetrahedral AB 5 5 0 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry AB 3 3 0 trigonal planar trigonal planar trigonal bipyramidal trigonal bipyramidal

10. 10.1

11. AB 2 2 0 linear linear VSEPR 10.1 AB 4 4 0 tetrahedral tetrahedral AB 6 6 0 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry AB 3 3 0 trigonal planar trigonal planar AB 5 5 0 trigonal bipyramidal trigonal bipyramidal octahedral octahedral

12. 10.1

13. 10.1

14. bonding-pair vs. bonding pair repulsion lone-pair vs. lone pair repulsion lone-pair vs. bonding pair repulsion > >

15. VSEPR AB 3 3 0 trigonal planar trigonal planar AB 2 E 2 1 10.1 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry trigonal planar bent

16. VSEPR AB 3 E 3 1 AB 4 4 0 tetrahedral tetrahedral 10.1 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry tetrahedral trigonal pyramidal

17. VSEPR AB 4 4 0 tetrahedral tetrahedral 10.1 AB 2 E 2 2 2 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry AB 3 E 3 1 tetrahedral trigonal pyramidal tetrahedral bent H O H

18. VSEPR 10.1 AB 5 5 0 trigonal bipyramidal trigonal bipyramidal AB 4 E 4 1 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry trigonal bipyramidal See-Saw (distorted tetrahedron)

19. VSEPR 10.1 AB 5 5 0 trigonal bipyramidal trigonal bipyramidal AB 3 E 2 3 2 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry AB 4 E 4 1 trigonal bipyramidal See-Saw trigonal bipyramidal T-shaped Cl F F F

20. VSEPR 10.1 AB 5 5 0 trigonal bipyramidal trigonal bipyramidal AB 2 E 3 2 3 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry AB 4 E 4 1 trigonal bipyramidal See-Saw AB 3 E 2 3 2 trigonal bipyramidal T-shaped trigonal bipyramidal linear I I I

21. VSEPR 10.1 AB 5 E 5 1 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry AB 6 6 0 octahedral octahedral octahedral square pyramidal Br F F F F F

22. VSEPR 10.1 AB 4 E 2 4 2 Class # of atoms bonded to central atom # lone pairs on central atom Arrangement of electron pairs Molecular Geometry AB 6 6 0 octahedral octahedral AB 5 E 5 1 octahedral square pyramidal octahedral square planar Xe F F F F

23. 10.1

24. Predicting Molecular Geometry Draw Lewis structure for molecule. Count number of lone pairs on the central atom and number of atoms bonded to the central atom. Use VSEPR to predict the geometry of the molecule. AB 2 E bent AB 4 E See-Saw (distorted Tetrahedron) 10.1 What are the molecular geometries of SO 2 and SF 4 ? (In SF 4 , S uses an expanded octet of 10.) S F F F F S O O S O O

25. Parent shapes for EX n molecules (n = 2-5) Formula n shape shapes of structures EX 2 2 linear EX 3 3 trigonal planar EX 4 4 tetrahedral EX 5 5 trigonal bipyramidal

26. Parent shapes for EX n molecules (n = 6-8) Formula n shape shapes of structures EX 6 6 octahedral EX 7 7 pentagonal bipyramidal EX 8 8 square antiprismatic

27. Final structures for VSEPR theory.

28. More final structures for VSEPR.

29. Dipole Moments and Polar Molecules 10.2 electron rich region electron poor region H F  

30. 10.2

31. 10.2 dipole moment polar molecule no dipole moment nonpolar molecule dipole moment polar molecule no dipole moment nonpolar molecule Which of the following molecules have a dipole moment? H 2 O, CO 2 , SO 2 , and CH 4 O H H S O O C O O C H H H H

32. 10.2 Chemistry In Action: Microwave Ovens

33. Valence bond theory – bonds are formed by sharing of e - from overlapping atomic orbitals. Sharing of two electrons between the two atoms. 10.3 Bond Dissociation Energy Bond Length H 2 F 2 436.4 kJ/mole 150.6 kJ/mole 74 pm 142 pm Overlap Of 2 1s 2 2p How does Lewis theory explain the bonds in H 2 and F 2 ?

34. Stop here

35. 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 10.4

36. 10.4

37. Formation of sp 2 Hybrid Orbitals 10.4

38. Formation of sp Hybrid Orbitals 10.4

39. # of Lone Pairs + # of Bonded Atoms Hybridization Examples 2 3 4 5 6 sp sp 2 sp 3 sp 3 d sp 3 d 2 BeCl 2 BF 3 CH 4 , NH 3 , H 2 O PCl 5 SF 6 Count the number of lone pairs AND the number of atoms bonded to the central atom 10.4 How do I predict the hybridization of the central atom?

40. 10.4

41. Sigma (  ) and Pi Bonds (  ) Single bond 1 sigma bond Double bond 1 sigma bond and 1 pi bond Triple bond 1 sigma bond and 2 pi bonds  bonds = 6 + 1 = 7  bonds = 1 10.5 How many  and  bonds are in the acetic acid (vinegar) molecule CH 3 COOH? C H H C H O O H

42. 10.5 Sigma bond (  ) – electron density between the 2 atoms Pi bond (  ) – electron density above and below plane of nuclei of the bonding atoms

43. 10.5

44. 10.5

45. Molecular orbital theory – bonds are formed from interaction of atomic orbitals to form molecular orbitals. No unpaired e - Should be diamagnetic Experiments show O 2 is paramagnetic (has UNPAIRED e-) 10.6 MO Theory is NOT in the AP Chemistry Curriculum and will NOT be on the AP exam! This is just a quick overview! O O

46. Energy levels of bonding and antibonding molecular orbitals in hydrogen (H 2 ). A bonding molecular orbital has lower energy and greater stability than the atomic orbitals from which it was formed. An antibonding molecular orbital has higher energy and lower stability than the atomic orbitals from which it was formed. 10.6

47. 10.6

49. The number of molecular orbitals (MOs) formed is always equal to the number of atomic orbitals combined. The more stable the bonding MO, the less stable the corresponding antibonding MO. The filling of MOs proceeds from low to high energies. Each MO can accommodate up to two electrons. Use Hund’s rule when adding electrons to MOs of the same energy. The number of electrons in the MOs is equal to the sum of all the electrons on the bonding atoms. 10.7 Molecular Orbital (MO) Configurations

50. 10.7 bond order ½ 1 0 ½ bond order = 1 2 Number of electrons in bonding MOs Number of electrons in antibonding MOs ( - )

51. Delocalized molecular orbitals are not confined between two adjacent bonding atoms, but actually extend over three or more atoms. 10.8

52. 10.6