1. methane, CH 4 less repulsion between the bonding pairs of electrons 109.5° 90°

2. .. ammonia NH 3

3. .. 109.5° (109.5°) 109.5° (107°) 109.5° (104.5°) water, H 2 O

5. Ozone O 3

6. Formaldhyde H 2 CO

7. Hydrogen Cyanide HCN

10. Are there atomic orbitals on C, Si, N and O to accommodate the bonding electrons of the shapes predicted by VSEPR? s orbital 3 p orbitals x y z x y z

11. x y z x y z Are there atomic orbitals on C, Si, N and O to accommodate the bonding electrons of the shapes predicted by VSEPR?

12. 4 sp 3 orbitals x y z Are there atomic orbitals on C, Si, N and O to accommodate the bonding electrons of the shapes predicted by VSEPR?

13. 4 sp 3 orbitals x y z C H H H H

14. s + p x + p y = 3 sp 2 orbitals p z orbital

16. O C H H

17. C O H H

18. s + p x = 2 sp orbitals P y orbital P z orbital

19. C N

20. CN

21. CN

22. CN

23. CN H

24. VSEPR shape bonding hybrid orbitals tetrahedral trigonal planar linear sp 3 sp 2 sp

25. Review: Ethane sp 3 C sp3 -H s C sp3 -C sp3

26. Review: Ethane sp 3 H C H H H H H C ● ● C sp3 -H s C sp3 -C sp3

27. Hybrid atomic orbitals Why are hybrid orbitals used in chemical bonding? s orbital and s - p x + - p orbital x p x s +....

28. molecular orbitals. a C-C bond energy Csp 3

29. molecular orbitals. a C-C bond energy Csp 3

30. CC H H C H H C H H H H A model of ethylene using hybrid and atomic orbitals.

31. molecular orbitals. a C=C bond energy Csp 2

32. H H C H H C H H H H A model of ethene using hybrid and atomic orbitals. CC

33. H H C H H C CC HH H H

34. H H C H H C CC H HH H · · · · σ -bond π -bond

35. H H O C : : molecular orbitals. a C=O bond

36. A model of methyl aldehyde using hybrid and atomic orbitals. H H O C CO H HH H · · · · : :

37. In contrast to the rotation about single bonds, the rotation about double bonds is very difficult. energy 12 kJ C

38. 2p x 2p z 2p y 2s

39. Important consequences of Quantum Mechanics The locations of the electrons are described The locations of the electrons are described by atomic orbitals. by atomic orbitals. A given orbital can contain only 2 electrons. (Pauli exclusion principle.) Atomic orbitals on different atoms will can combine to give molecular orbitals, but only if their symmetry matches. Each orbital has an associated energy and electrons will occupy the lowest energy orbitals first. good  bond bad – wrong symmetry No bonding! No bonding!

40. C, N, O s orbital p orbitals H x y z These atomic orbitals and their hybrids will be used extensively in our models of chemical bonding.

41. Common hybrid orbitals used in bonding of carbon, nitrogen and oxygen. sp x y z 2s 2p z 2p x 2p y

42. Common hybrid orbitals used in bonding of carbon, nitrogen and oxygen. sp hybrid orbital angle 180° sp sp pzpzpzpz pypypypy2s 2p z 2p x 2p y

43. Common hybrid orbitals used in bonding of carbon, nitrogen and oxygen. sp 2 2s 2p z 2p x 2p y hybrid orbital angle 120° pzpzpzpz

44. Common hybrid orbitals used in bonding of carbon, nitrogen and oxygen. sp 3 2s 2p z 2p x 2p y hybrid orbital angle 109.5°

45. Methane sp 3 H H C H H H C sp3 -H s

46. Ethane sp 3 H H H C H

47. Ethane H C H H ● H H H C ●

48. Ethane H C H H H H H C ● ● C sp3 -H s C sp3 -C sp3

49. Ethane sp 3 C sp3 -H s C sp3 -C sp3