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VSEPR
Valence Shell Electron Pair Repulsion
 Electron pairs orient themselves so as to make the angles
between themselves as large as possible
 Repulsion follows Coulomb’s law
 This includes bonded as well as non-bonded pairs
Molecular Geometry
 Non-bonded pairs are not seen on the molecule but they do
affect it
 In determining molecular geometries, multiple bonds are
considered like single bonds
 Six types of molecular geometries
Electron Pair Geometry
 Geometry if unshared pair thought of as a bond
Linear Molecular and Electron-Pair
Geometry
 Two bonded pair and no non-bonded pairs on central atom
 180°
Trigonal Planer Molecular and ElectronPair Geometry
 Three bonded pair and no non-bonded pairs
 120° between bonds
Bent Molecular and Trigonal Planer
Electron-Pair Geometry
 Two bonded pair and one non-bonded pair
 120° between bonds
Tetrahedral Molecular and ElectronPair Geometry
 Four bonded pairs
 109.5° between bonds
Trigonal Pyramidal Molecular and
Tetrahedral Electron-Pair Geometry
 Three bonded and one non-bonded
 109.5° between bonds
Bent Molecular and Tetrahedral
Electron-Pair Geometry
 Two bonded and two non-bonded
 104.5° between bonds
Non-Bonding Pairs
 Exert greater repulsive forces on adjacent pairs than bonded
electrons do
 Example – All of these have tetrahedral electron pair
geometries
 CH4
109.5°
 NH3 107°
 H2O 104.5°
More Geometries of Expanded Octets