1. Modern Chemistry Chapter 6 Chemical Bonding
Sections 1-5
Introduction to Chemical Bonding
Covalent Bonding & Molecular Compounds
Ionic Bonding & Ionic Compounds
Metallic Bonding
Molecular Geometry
Chapter 6 Section 5 Molecular Geometry pages

2. Chapter 6 Section 5 Molecular Geometry pages 197-207
VSEPR theory
Hybridization
Hybrid orbitals
Dipole
Hydrogen bonding
London dispersion forces
Chapter Vocabulary
Chapter 6 Section 5 Molecular Geometry pages

3. Chapter 6 Section 5 Molecular Geometry pages 197-207

4. Chapter 6 Section 5 Molecular Geometry pages 197-207
VSEPR Theory
Valence-Shell Electron-Pair Repulsion
Repulsions between the set of valence-level electrons surrounding an atom causes these sets to be oriented as far apart as possible.
Chapter 6 Section 5 Molecular Geometry pages

5. VSPRE & Molecular Geometry
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Chapter 6 Section 5 Molecular Geometry pages

6. Chapter 6 Section 5 Molecular Geometry pages 197-207
Geometry & Lone Pairs
Chapter 6 Section 5 Molecular Geometry pages

7. Chapter 6 Section 5 Molecular Geometry pages 197-207
LINEAR
Example formula: BeF2
Type of molecule: AB2
Bond angle: 180°
Shared pairs on the central atom: 2
Unshared pairs on the central atom: 0 : : :F
- Be - F: : :
Chapter 6 Section 5 Molecular Geometry pages

8. Chapter 6 Section 5 Molecular Geometry pages 197-207
TRIGONAL PLANAR
Example formula: BF3
Type of molecule: AB3
Bond angle: 120°
Shared pairs on the central atom: 3
Unshared pairs on the central atom: 0 :F : F: : B
:F: :
Chapter 6 Section 5 Molecular Geometry pages

9. Chapter 6 Section 5 Molecular Geometry pages 197-207
TETRAHEDRAL
Example formula: CH4
Type of molecule: AB4
Bond angle: 109.5°
Shared pairs on the central atom: 4
Unshared pairs on the central atom: 0 H C H H H
Chapter 6 Section 5 Molecular Geometry pages

10. Chapter 6 Section 5 Molecular Geometry pages 197-207
ANGULAR
Example formula: H2O
Type of molecule: AB2E2
Bond angle: 105°
Shared pairs on the central atom: 2
Unshared pairs on the central atom: 2 O : : H H
Chapter 6 Section 5 Molecular Geometry pages

11. Chapter 6 Section 5 Molecular Geometry pages 197-207
TRIGONAL PYRAMIDAL
Example formula: NH3
Type of molecule: AB3E
Bond angle: 107°
Shared pairs on the central atom: 3
Unshared pairs on the central atom: 1 : N H H H
Chapter 6 Section 5 Molecular Geometry pages

12. Chapter 6 Section 5 Molecular Geometry pages 197-207
Unshared pairs occupies more space around the central atom than shared pairs
Unshared pairs repel other electrons more strongly than shared pairs
Multiple bonds are treated the same as single bonds
Polyatomic ions are treated like molecules.
Chapter 6 Section 5 Molecular Geometry pages

13. Chapter 6 Section 5 Molecular Geometry pages 197-207
CO2
ClO3 1-
Practice Problems page 201
CF4
NO3 1-
Chapter 6 Section 5 Molecular Geometry pages

14. Chapter 6 Section 5 Molecular Geometry pages 197-207
Hybridization
The mixing of two or more atomic orbitals of similar energies on the same atom to produce new hybrid atomic orbitals of equal energy
Example CH4
C =   _ _ __
1s 2s 2p
 _ _ _ _
1s sp3
Chapter 6 Section 5 Molecular Geometry pages

15. Chapter 6 Section 5 Molecular Geometry pages 197-207
Hybridization
s and p orbitals have different shapes
The 2s & 2p hybridize to make four identical orbitals
named sp3
The 3 is from the three p orbitals used
But the 1 is not written for the s
Chapter 6 Section 5 Molecular Geometry pages

16. Chapter 6 Section 5 Molecular Geometry pages 197-207
Hybridization
All sp3 orbitals have the same energy
Higher than 2s but
Lower than 2p
Hybrid orbitals – orbitals of equal energy produced by the combination of two or more orbitals.
Chapter 6 Section 5 Molecular Geometry pages

17. Chapter 6 Section 5 Molecular Geometry pages 197-207
Hybridization
N =   _ _ _
1s 2s 2p
  _ _ _
1s sp3
O =    _ _
   _ _
Chapter 6 Section 5 Molecular Geometry pages

18. Chapter 6 Section 5 Molecular Geometry pages 197-207
Hybridization
Be =  
1s 2s
 _ _ __
1s sp
B =   _ __ __
1s 2s 2p
 _ _ _ __
1s sp2
Uses one p orbital
Uses two p orbitals
Chapter 6 Section 5 Molecular Geometry pages

19. Chapter 6 Section 5 Molecular Geometry pages 197-207
Hybridization
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Chapter 6 Section 5 Molecular Geometry pages

20. Hybrid Orbital Animation
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Chapter 6 Section 5 Molecular Geometry pages

21. Comparing Molecular & Ionic Compounds
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Chapter 6 Section 5 Molecular Geometry pages

22. Chapter 6 Section 5 Molecular Geometry pages 197-207
Molecule Polarity δ+ δ-
H - Cl
2.1
3.0
Lower EN
Higher EN
polar bond = dipole
Dipole: created by equal but opposite charges that are separated by a short distance
Chapter 6 Section 5 Molecular Geometry pages

23. bond polarity and molecule geometry.
Molecule Polarity
Molecule polarity for compounds with more than one bond depends on …
bond polarity and molecule geometry.
Chapter 6 Section 5 Molecular Geometry pages

24. Chapter 6 Section 5 Molecular Geometry pages 197-207
Molecule Polarity
Draw the Lewis Structure true to shape. Example NH3 N H :
Chapter 6 Section 5 Molecular Geometry pages

25. Chapter 6 Section 5 Molecular Geometry pages 197-207
Molecule Polarity
Find all the partial positive and negatives for each atom in the molecule δ-
3.0 : N
2.1 H H H δ+ δ+ δ+
High EN = δ Low EN = δ+
Look at each bond.
Chapter 6 Section 5 Molecular Geometry pages

26. H N : H H Molecule Polarity
Look at around the “outside” of the molecule. δ- : N H H H δ+ δ+ δ+
All the same δ = NP; Different δ = P
Chapter 6 Section 5 Molecular Geometry pages

27. Chapter 6 Section 5 Molecular Geometry pages 197-207
Molecule Polarity
Draw the Lewis Structure true to shape. Example CH4 C H
Chapter 6 Section 5 Molecular Geometry pages

28. Chapter 6 Section 5 Molecular Geometry pages 197-207
Molecule Polarity
Find all the partial positive and negatives for each atom in the molecule δ+ C H
2.1
2.5 δ-
2.1 δ+ δ+
2.1
2.1 δ+
Look at each bond.
High EN = δ Low EN = δ+
Chapter 6 Section 5 Molecular Geometry pages

29. C H Molecule Polarity Look at around the “outside” of the molecule. δ+δ- δ+ δ+ δ+
Carbon is not on the “outside”.
All the same δ = NP; Different δ = P
Chapter 6 Section 5 Molecular Geometry pages

30. Intermolecular Forces
The force of attraction between molecules to make (solids or) liquids
Boiling point is a good measure of the strength of intermolecular forces
Weaker than covalent bonds, ionic bonds and metallic bonds
Chapter 6 Section 5 Molecular Geometry pages

31. Chapter 6 Section 5 Molecular Geometry pages 197-207
Molecule Polarity
H - Cl δ+ δ-
H - Cl δ+ δ-
Dipole-dipole force: the force of attraction between polar molecules
Chapter 6 Section 5 Molecular Geometry pages

32. Dipole Dipole Animation
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Chapter 6 Section 5 Molecular Geometry pages

33. Comparing Dipole Dipole Forces
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Chapter 6 Section 5 Molecular Geometry pages

34. Chapter 6 Section 5 Molecular Geometry pages 197-207
Hydrogen Bonding
H-F, H-O or H-N bonds have a large electronegativity difference
These bonds are very polar.
Molecules with these bonds have very strong dipole-dipole forces
Chapter 6 Section 5 Molecular Geometry pages

35. Chapter 6 Section 5 Molecular Geometry pages 197-207
Hydrogen Bonding
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Chapter 6 Section 5 Molecular Geometry pages

36. Chapter 6 Section 5 Molecular Geometry pages 197-207
Hydrogen Bonding
The intermolecular force in which a Hydrogen atom that is bonded to Nitrogen or Oxygen or Fluorine is attracted to an unshared pair of electrons of the N, O or F of another molecule
Chapter 6 Section 5 Molecular Geometry pages

37. Chapter 6 Section 5 Molecular Geometry pages 197-207
Hydrogen Bonding
Compare PH3 & NH3 H2O & H2S Page 204
Chapter 6 Section 5 Molecular Geometry pages

38. Chapter 6 Section 5 Molecular Geometry pages 197-207
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Dipole Induced Dipole
Chapter 6 Section 5 Molecular Geometry pages

39. Chapter 6 Section 5 Molecular Geometry pages 197-207
Induced Dipole
Polar molecules cause a dipole in a nonpolar molecule H δ+ δ- δ+ : : : O O O δ- : : : H δ+
Chapter 6 Section 5 Molecular Geometry pages

40. London Dispersion Forces
Nonpolar molecules don’t have dipoles
However at any instance the electron distribution may be uneven.
An instantaneous dipole can occur and induce dipoles in other molecules
Chapter 6 Section 5 Molecular Geometry pages

41. London Dispersion Force
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Chapter 6 Section 5 Molecular Geometry pages

42. London Dispersion Forces
London dispersion forces – the intermolecular attraction resulting from the constant motion of electrons and the creation of instantaneous dipoles
Very weak intermolecular forces
London forces increase with increasing atomic or molar mass.
Chapter 6 Section 5 Molecular Geometry pages

43. Lewis Structures Practice
C2H4
BeF2
AsH3
IBr
CHCl3
CN 1-
N2O2
Lewis Structures Practice
Chapter 6 Section 5 Molecular Geometry pages

44. Lewis Structures Practice
C2Cl4
SCl2
AsF5
CI2Cl2
BF3
NO 1-
CH2O
IO3 1-
Lewis Structures Practice
Chapter 6 Section 5 Molecular Geometry pages

45. Section 5 Homework Chapter 6 Section 5 Worksheet
Chapter 6 Section 5 Molecular Geometry pages