Molecular Structure VSEPR Model. VSEPR Valence Shell Electron Pair Repulsion The structure around a...
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Transcript of Molecular Structure VSEPR Model. VSEPR Valence Shell Electron Pair Repulsion The structure around a...
Molecular StructureVSEPR Model
VSEPRValence Shell Electron Pair Repulsion
The structure around a given atom is determined principally by minimizing electron-pair repulsions
Non-bonding and bonding electrons pairs will be as far apart as possible
Examples CO2
• BF3
CH4
Effect of Unshared Electron Pairs
The ideal tetrahedral angle is 109.5°
Lone (unshared) electron pairs require more room than bonding pairsThey have greater repulsive forcesTend to compress the angles between bonding
pairs
Lone pairs do not cause distortion when bond angles are 120° or greater
Multiple BondsMultiple bonds count as one effective electron
pair
When a molecule exhibits resonance, ANY of the resonance structures can be used to predict the molecular structure using the VSEPR model
No Single Central AtomApply the principal of distancing shared and
unshared electron pairs
Look at real 3D models to develop predictive skills
VSEPR ModelsFor non-ionic compounds –
works in most cases