Molecular Shape Section 9.4

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Molecular ShapeSection 9.4

• Chemistry

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Objectives

• Discuss the VSEPR bonding theory
• Predict the shape of and the bond angles in a
  molecule
• Define hybridization

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The Shape of Molecules

• The shape of molecules determines reaction
  ability
• The model we use is the VSEPR model
• Valence Shell Electron Pair Repulsion

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VSEPR Model

• Minimizes the repulsion of shared and unshared
  pairs of electrons around the central atom
• 7 key shapes you will need to be able to draw and
  identify

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Linear Molecular Shape

• Example BeCl2
• Total Pairs of Electrons 2
• Shared Pairs of Electrons 2
• Lone Pairs 0
• Bond Angle 180
• Hybrid Orbitals sp

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Trigonal Planar

• Example AlCl3
• Total Pairs of Electrons 3
• Shared Pairs of Electrons 3
• Lone Pairs of Electrons 0
• Bond Angle 120
• Hybrid Orbitals sp²

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Tetrahedral

• Example CH4
• Total Pairs of Electrons 4
• Shared Pairs of Electrons 4
• Lone Pairs of Electrons 0
• Bond Angle 109.5
• Hybrid Orbitals sp³

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Trigonal Pyramidal

• Example PH3
• Total Pairs of Electrons 4
• Shared Pairs of Electrons 3
• Lone Pairs of Electrons 1
• Bond Angle 107.3
• Hybrid Orbitals sp³

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Bent

• Example H2O
• Total Pairs of Electrons 4
• Shared Pairs of Electrons 2
• Lone Pairs of Electrons 2
• Bond Angle 104.5
• Hybrid Orbitals sp³

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Trigonal Bipyramidal

• Example NbBr5
• Total Pairs of Electrons 5
• Shared Pairs of Electrons 5
• Lone Pairs of Electrons0
• Bond Angle 90, 120
• Hybrid Orbitals sp³d

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Octahedral

• Example SF6
• Total Pairs of Electrons 6
• Shared Pairs of Electrons 6
• Lone Pairs of Electrons 0
• Bond Angle 90
• Hybrid Orbitals sp³d²

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Hybridization

• Hybridization A process in which atomic
  orbitals are mixed to form new, identical hybrid
  orbitals
• Carbon is the most common
• The number of hybrid orbitals the number of
  total pairs of electrons

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Homework

• 54-59 on page 262