The two unhybridized 2p orbitals can overlap to form a pi-bond between the carbon atoms.

1. The two unhybridized 2p orbitals can overlap to form a pi-bond between the carbon atoms. pi-bond: (π-bond) A pi-bond has the electron density concentrated in two separate regions that lie on opposite sides of the imaginary line connecting the two nuclei.

2. C2H4 with the pi-overlap shown.

3. C2H4 with a more realistic representation of the pi-overlap shown.

4. Electron density representation for C2H4.

5. Wedge-bond perspective diagram for C2H4.

6. The double bond in C2H4 is represented as C C. Keep in mind that it is made up of a sigma bond and a pi bond.

7. The double bond in C2H4 is represented as C C. Keep in mind that it is made up of a sigma bond and a pi bond. The overall strength of the C Cbond is due to both the σ and π bonds.

8. Acetylene, C2H2: This is a linear molecule.

9. Acetylene, C2H2: This is a linear molecule. The hybridization scheme is as follows:

10. Acetylene, C2H2: This is a linear molecule. The hybridization scheme is as follows: (ground state of carbon) 2s 2p

11. Acetylene, C2H2: This is a linear molecule. The hybridization scheme is as follows: (ground state of carbon) 2s 2p (promotion of electron)

12. Acetylene, C2H2: This is a linear molecule. The hybridization scheme is as follows: (ground state of carbon) 2s 2p (promotion of electron)

13. Acetylene, C2H2: This is a linear molecule. The hybridization scheme is as follows: (ground state of carbon) 2s 2p (promotion of electron) sp hybrid p orbitals

14. The two sp hybrids orbitals on each carbon atom are used to form a sigma bond with a hydrogen 1s orbital and another sigma bond with the other carbon atom.

15. The two sp hybrids orbitals on each carbon atom are used to form a sigma bond with a hydrogen 1s orbital and another sigma bond with the other carbon atom. The unhybridized p orbitals on each carbon atom form two pi-bonds.

16. Acetylene C2H2

17. Acetylene C2H2

18. Other hybrid orbitals

19. Other hybrid orbitals To form more than 4 equivalent bonds, it is necessary to involve the d-orbitals.

20. hybridmixedorientationinspace orbitals ____________________________________ sp s+plinear ____________________________________

21. hybridmixedorientationinspace orbitals ____________________________________ sp s+plinear sp2s+p+ptrigonal planar ____________________________________

22. hybridmixedorientationinspace orbitals ____________________________________ sp s+plinear sp2s+p+ptrigonal planar sp3s+p+p+ptetrahedral ____________________________________

23. hybridmixedorientationinspace orbitals ____________________________________ sp s+plinear sp2s+p+ptrigonal planar sp3s+p+p+ptetrahedral sp3d s+p+p+p+dtrigonalbipyramid ____________________________________

24. hybridmixedorientationinspace orbitals ____________________________________ sp s+plinear sp2s+p+ptrigonal planar sp3s+p+p+ptetrahedral sp3d s+p+p+p+dtrigonalbipyramid sp3d2 s+p+p+p+d+d octahedral ____________________________________

31. PCl5 involves sp3d hybrid orbitals on the P atom.

32. SF6 involves sp3d2 hybrid orbitals on the S atom.

33. Hybridization in molecules with lone pairs example, NH3:

34. Hybridization in molecules with lone pairs example, NH3: (ground state of N)

35. Hybridization in molecules with lone pairs example, NH3: (ground state of N) sp3

36. Hybridization in molecules with lone pairs example, NH3: (ground state of N) sp3 One of the sp3 hybrid orbitals contains a lone pair.

37. Hybridization in molecules with lone pairs example, NH3: (ground state of N) sp3 One of the sp3 hybrid orbitals contains a lone pair. The sp3 hybrid orbitals are directed towards the vertices of a regular tetrahedron.

38. Because of repulsion between the lone pair electrons and those in the bonding orbitals, the bond angle decreases from 109o28’to 107.3o.

39. Ammonia, NH3

40. A similar description using hybrid orbitals can be employed for H2O.

41. Conformations and Multiple Bonding

42. Conformations and Multiple Bonding In molecules involving single bonds, e.g.

43. Conformations and Multiple Bonding In molecules involving single bonds, e.g. ethane

44. Conformations and Multiple Bonding In molecules involving single bonds, e.g. ethane

45. Conformations and Multiple Bonding In molecules involving single bonds, e.g. ethane The overlap of the orbitals for the C Cbond is hardly affected at all if one portion of the molecule rotates relative to the other about the bond axis.

46. Such rotation is said to occur freely – called free rotation because the energy cost is approximately zero.

47. Such rotation is said to occur freely – called free rotation because the energy cost is approximately zero. Free rotation permits different possible relative orientations of the atoms in the molecule.

48. Such rotation is said to occur freely – called free rotation because the energy cost is approximately zero. Free rotation permits different possible relative orientations of the atoms in the molecule. The different relative orientations are called conformations.