Chapter 3 Simple Bonding Theory

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Chapter 3Simple Bonding Theory

• Lewis Dot Structures
• Resonance
• Formal Charge
• VSEPR the subtle effects

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Lewis Dot Structures

• 1. Count valence electrons
• 2. Arrange atoms
• 3. Add bonds
• 4. Add lone pairs
• 5. Convert lone pairs to bonding pairs (octet
  rule and exceptions)

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Lewis Dot Structures

• ExamplesCO2SO3N2OXeF4ClF3PCl6

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Why does the octet rule work?
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More complex

• NO2
• NO

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• Formal Charge
• Group - unshared electrons on atom -
  bonds to atom
• Example O3

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Resonance

• Example SO3

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Resonance and Formal Charge

• Example SCN-

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Resonance and Formal Charge

• Example SCN-

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Octet Rule vs. Pi Bonding Trends

• BeF2 and
• BF3

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Octet Rule vs. Formal Charge

• Always follow octet ruleExceptions? SO42-

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VSEPR

• Maximize personal space
• CO2, SO3, SO42, PCl5, SF6
• Lone pairs vs. bonding pairs?
• Single bonds vs. multiple bonds?
• Electronegativity effects

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VSEPR
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Lone Pair Effects!
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Pi Bonds vs. Lone Pairs Guess these bond angles.
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Pi Bonds vs. Lone Pairs
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Pi Bonds vs. Lone Pairs
Which take up more room lone pairs or a pi bond?
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Electronegativity Effects
Molecule X-P-X Angle o PF3
97.8 PCl3
100.3 PBr3
101
Explain this trend.
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Electronegativity Effects
Molecule H-X-H Angle o H2O
104.4 H2S
92.1 H2Se
90.6
Explain this trend.
Molecule X-As-X Angle o AsF3
AsCl3
AsBr3
Predict this trend.