1. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 1 Covalent Bonding: Hybrid Atomic Orbitals

2. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 2 Bonding –Write Lewis Structures. –Determine the Arrangement of e - pairs using VSEPR Theory. –Determine the hybrid atomic orbitals used to form bonds.

3. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 3 Hybridization The mixing of atomic orbitals to form special orbitals for bonding. The atoms are responding as needed to give the minimum energy for the molecule.

4. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 4 Hybrid Orbitals Orbitals used to describe bonding that are obtained by taking combinations of atomic orbitals of the isolated atoms.

5. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 5 Figure 9.1 (a) Lewis Structure (b) Tetrahedral Molecular Geometry of the Methane Molecule By experiment, CH 4 know to be tetrahedral with bond angles of 109.5 . Experiments show 4 equivalent bonds.

6. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 6 Valence electrons of carbon: 2s 2 2p 2

7. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 7 Figure 9.2 The Valence Orbitals on a Free Carbon Atom: 2s, 2p x, 2p y, and 2p z Bonding assumed to involve only the valence electrons. Overlap with these orbitals would not give 109.5  bond angles.

8. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 8 Hybridization ☻☻☻ A new set of atomic orbitals might better serve the C atom in forming molecules.

9. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 9 Hybridization ☻☻☻ Hybridization = Modification of model to account for the observation. Atoms seem to use special orbitals when forming molecules.

10. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 10 Figure 9.3 The Formation of sp 3 Hybrid Orbitals “sp 3 hybridization.”

11. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 11 Figure 9.5 An Energy-Level Diagram Showing the Formation of Four sp 3 Orbitals Four equivalent carbon orbitals.

12. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 12 Figure 9.6 Tetrahedral Set of Four sp 3 Orbitals

13. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 13 Figure 9.7 The Nitrogen Atom in Ammonia is sp 3 Hybridized

14. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 14 Ethylene H 2 C==CH 2 Each carbon atom is surrounded by three effective pairs. Requires a set of 3 orbitals with a trigonal planar geometry and 120  bond angles.

15. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 15 Figure 9.8 The Hybridization of the s, p x, and p y Atomic Orbitals

16. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 16 Figure 9.9 An Orbital Energy-Level Diagram for sp 2 Hybridization One 2p orbital of carbon is not used..

17. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 17 Figure 9.10 An sp 2 Hybridized C Atom

18. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 18  (sigma) bonds

19. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 19 Figure 9.11 The  Bonds in Ethylene

20. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 20 Double Bond Double bond results from an additional bond----- a  (pi) bond.

21. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 21 Figure 9.12 Sigma and Pi Bonding

22. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 22 Figure 9.13 The Orbitals for C 2 H 4

23. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 23 Whenever an atom is surrounded by 3 effective e - pairs, a set of sp 2 hybrid orbitals is required.

24. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 24 A sigma (  ) bond centers along the internuclear axis. A pi (  ) bond occupies the space above and below the internuclear axis. Double Bonds

25. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 25 CO 2 O==C==O 2 effective pairs around central atom at an angle of 180 

26. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 26 Figure 9.14 When One s Orbital and One p Orbital are Hybridized, a Set of Two sp Orbitals Oriented at 180 Degrees Results

27. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 27 Figure 9.16 The Orbital Energy-Level Diagram for the Formation of sp Hybrid Orbitals on Carbon A set of two sp orbitals.

28. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 28 Figure 9.17 The Orbitals of an sp Hybridized Carbon Atom Two sp hybridized orbitals. Two p unhybrized Orbitals.

29. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 29 Sigma Bonds

30. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 30 Figure 9.19 The Orbitals for CO 2

31. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 31 PCl 5 5 e - pairs requires a geometry of trigonal bipyramidal. Requires dsp 3 hybridization.

32. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 32 Figure 9.21 A Set of dsp 3 Hybrid Orbitals on a Phosphorus Atom

33. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 33 Each Cl is surrounded by 4 e - pairs. They require sp 3 hybridization.

34. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 34 Figure 9.22 (a) The Structure of the PCl 5 Molecule (b) The Orbitals Used to Form the Bonds in PCl 5

35. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 35 SF 6 6 e - pairs requires a geometry of octahedral. Requires d 2 sp 3 hybridization.

36. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 36 Figure 9.23 An Octahedral Set of d 2 sp 3 Orbitals on a Sulfur Atom

37. Copyright©2000 by Houghton Mifflin Company. All rights reserved. 37 The Localized Electron Model 4 Draw the Lewis structure(s) 4 Determine the arrangement of electron pairs (VSEPR model). 4 Specify the necessary hybrid orbitals.