Term
Sidgwick and Powell 1940
Geometry depends on electron pairs
Gillespie and Nyholm arrangement determined by repulsive interactions
A lone pair causes deviation from the ideal bond angel which in turn changes the geometry of molecules.
Minimum repulsion should be between the electron pairs
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Definition
Applications
AB2 system
2 bond pairs, 0 lone pairs
Linear geometry
Bond angle is 180
Hybridization sp
E.g. becl2 beh2
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Term
AB2 with multiple bonds (CO2)
AB3 with no lone pair
3 BP, 0 lp
Trigonal planar geometry
Bond angle 120
E.g. bf3, bcl3, alcl3, gah3, InH3
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Definition
AB2E
2 bp, 1 Lp
Sp2 hyb
T planar
Bond angle less than 120 due to repulsion
4 valance e-
Group 14 element
PbCl2, SnCl2
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Term
AB3 multiple bonds SO3
AB4 system
CH4, SiCl4, CCl4, SiF4
109.5
Tetrahedral |
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Definition
AB3E
107.5
Total valance e around central atom : 3+2=5e
So grp 15 element
NH3, pcl3, AsH3, SbCl3, PH3
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Term
AB2E2
Total valance e = 6
H20 h2S
104.5 |
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Definition
AB5
PCl5, sp3d hybrid
Trigonal bipyramindal
90 between 3 bond pairs in equitoral plane
120 between e pair in axial and eq plane (single plane forming an equilateral triangle)
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Term
AB5
AB4E : see saw, sf4
AB3E2 : T shaped
Valance e are 7
So ClF3, BrF3
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Definition
AB6
Octahedron
Angle 90 each
SF6 no lp
Sp3d2 hybr |
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