Lecture _VSPER.pptx educational purpose only

Lecture _VSPER.pptx educational purpose only

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  Valence Shell Electron Pair Repulsion Theory Planar triangular Tetrahedral Trigonal pyramidal Bent
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  VSEPR theory assumesthat the shape of a molecule is determined by the repulsion of electron pairs. Molecular Shape
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  VSEPR Theory • Basedon Electron Dot (Lewis structures) • Theory predicts shapes of compounds • abbreviated VSEPR • VSEPR (pronounced “vesper”) stands for Valence Shell Electron Pair Repulsion • VSEPR predicts shapes based on electron pairs repelling (in bonds or by themselves) • Electrons around central nucleus repel each other. So, structures have atoms maximally spread out
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  VSEPR overview • Eachshape has a name (you will have to know these) • Names of Shapes: • tetrahedral • trigonal pyramidal • Bent • Linear • trigonal planar
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  Triangular Planar Tetrahedral Trigonal pyramidal Linear Bentor V Models
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  methane, CH4 Bonds areall evenly spaced electrons 109.5° Tetrahedral
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  Less repulsion betweenthe bonding pairs of electrons .. ammonia NH3 .. .. .. Trigonal Pyramidal
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  .. .. .. 109.5° (109.5°)109.5° (107°) 109.5° (104.5°) water, H2O
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  .. .. ..
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  Bent or V 2unshared pairs of e’s at top of O repel bonds and force them to bend
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  Molecule Lewis StructureNumber of electron pairs CH4 NH3 SHAPE Tetrahedral Trigonal Pyramidal 4 4 (3 shared 1 lone pair)
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  Molecule Lewis StructureNumber of electron pairs H2O CO2 SHAPE Bent or V 4 (2 shared 2 lone pairs) 2 Linear
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  Molecule Lewis StructureNumber of electron pairs BeCl2 BF3 SHAPE 2 3 Linear Trigonal Planar