1. Chapter 8 Covalent Bonding 8.3 Bonding Theories
8.1 Molecular Compounds
8.2 The Nature of Covalent Bonding
8.3 Bonding Theories
8.4 Polar Bonds and Molecules
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2. Valence Shell Electron Pair Repulsion Theory
VSEPR Theory
VSEPR Theory
Valence Shell Electron Pair Repulsion Theory
Explains 3 dimensional shape of molecules.
States that repulsion between electron pairs causes molecular shapes to adjust so valence-electron pairs stay as far apart as possible.
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3. 2 atoms bonded to central atom
VSEPR Theory
Linear
2 atoms bonded to central atom
No unshared electron pairs on central atom.
Double bonds joining oxygens to carbon are farthest apart when O=C=O bond angle is 180°
Carbon dioxide (CO2)
No unshared
electron pairs
on carbon
180°
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4. 2 atoms bonded to central atom 1 or 2 unshared electron pairs
VSEPR Theory
Bent
2 atoms bonded to central atom
1 or 2 unshared electron pairs
With two unshared pairs repelling the bonding pairs, the bond angle is compressed to ~105°
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5. 3 atoms bonded to the central atom
VSEPR Theory
Trigonal Planar
3 atoms bonded to the central atom
No unshared electron pairs.
The measured bond angle is 120°
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6. 3 atoms bonded to the central atom
VSEPR Theory
Trigonal Pyramidal
3 atoms bonded to the central atom
1 unshared electron pair that strongly repels the bonding pairs, pushing the bonding electrons together.
The measured bond angle is only 107°
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7. 4 atoms bonded to the central atom
VSEPR Theory
Tetrahedral
4 atoms bonded to the central atom
No unshared electron pairs.
All of the bond angles are 109.5°
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8. Here are some common molecular shapes.
VSEPR Theory
Here are some common molecular shapes.
Linear
Trigonal planar
Bent
Trigonal
Pyramidal
Tetrahedral
bipyramidal
Octahedral
Square
planar
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9. Molecular Shape Summary
VSEPR Theory
Molecular Shape Summary
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