CH4
H
Lewis Diagrams and
VSEPR Models
C
H
H C H
H
Chemistry Essentials - 022
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Molecules
Lewis Diagrams
VSEPR Model
Model
Alternatives
Resonance
Geometry
Coulombic repulsion
Formal charges
Extensions
Predict
Bond Angles
Bond Energy
Bond length
Polarity
Bond overlap
Odd valence
Molecular Orbital
Theory
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Drawing Lewis Structures
V
alence electrons
S
keleton
E
lectrons
P
airs of bonds?
R eview formal charges
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Drawing Lewis Structures
1+4+5 = 10
1 2 3 4 5 6 7 8
0
HCN
Drawing Lewis Structures
HCN
1+4+5 = 10 6
H
C
N
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Drawing Lewis Structures
HCN
1+4+5 = 10 6 0
H
C
N
H
C
N
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Drawing Lewis Structures
0
H
HCN
0
C
0
N
FC = Valence electrons - assigned electrons
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Drawing Lewis Structures
CO2
4+6+6=16
O
C
O
-1
0
+1
0
0
0
O
O
C
C
O
O
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Drawing Lewis Structures
6+6+6=18
O
-1
O
0
O3
O
O
+1
0
+1
-1
O
O
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Resonance
O
O
O
O
O
O
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VSEPR Model
Valence-Shell Electron-Pair Repulsion
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VSEPR Model
Valence-Shell Electron-Pair Repulsion
O
C
O
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VSEPR Model
Valence-Shell Electron-Pair Repulsion
O
180°
C
O
Linear
NOTE: Organic chemists call this sp
hybridized
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VSEPR Model
Valence-Shell Electron-Pair Repulsion
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VSEPR Model
Valence-Shell Electron-Pair Repulsion
120°
Trigonal planar
2
NOTE: Organic chemists call this sp
hybridized
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VSEPR Model
Valence-Shell Electron-Pair Repulsion
O
O
O
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VSEPR Model
Valence-Shell Electron-Pair Repulsion
O
O
O
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VSEPR Model
Valence-Shell Electron-Pair Repulsion
H
H C H
H
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VSEPR Model
Valence-Shell Electron-Pair Repulsion
109.5°
H
H C H
H
Tetrahedral
3
NOTE: Organic chemists call this sp
hybridized
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VSEPR Model
Valence-Shell Electron-Pair Repulsion
PCl5
SF6
Trigonal bipyramidal
Octahedral
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Extensions
1. Bond differences
Carboxylic acid
σ bonds
π bonds
1I. Odd valence electrons
Nitrogen dioxide
O
N
O
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Carboxylic acid
l
a
t
i
b
r
O
r
a
l
u
c
e
l
o
M
y
r
o
e
h
T
1I. Odd valence electrons
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Did you learn?
H20
To use Lewis diagrams and VSEPR to
predict geometry, hybridization and polarity.
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Acknowledgements
AJ. A Blue Balloon on a Ribbon, July 18, 2008. Open clip Art Library image’s page. http://commons.wikimedia.org/wiki/File:Blue_toy_balloon.svg.
“File:Acetic Acid Atoms.svg,” August 18, 2013. http://en.wikipedia.org/wiki/File:Acetic_acid_atoms.svg.
“File:AX4E0-3D-Balls.png,” August 16, 2013. http://en.wikipedia.org/wiki/File:AX4E0-3D-balls.png.
“File:AX6E0-3D-Balls.png,” August 18, 2013. http://en.wikipedia.org/wiki/File:AX6E0-3D-balls.png.
“File:Bent-3D-Balls.png,” August 17, 2013. http://en.wikipedia.org/wiki/File:Bent-3D-balls.png.
“File:Linear-3D-Balls.png,” August 17, 2013. http://en.wikipedia.org/wiki/File:Linear-3D-balls.png.
“File:Nitrate-Ion-Resonance-2D.png,” August 17, 2013. http://en.wikipedia.org/wiki/File:Nitrate-ion-resonance-2D.png.
“File:Nitrogen-Dioxide-3D-vdW.png,” August 17, 2013. http://en.wikipedia.org/wiki/File:Nitrogen-dioxide-3D-vdW.png.
“File:Pi-Bond.svg,” August 18, 2013. http://en.wikipedia.org/wiki/File:Pi-Bond.svg.
“File:Sigma Bond.svg,” August 18, 2013. http://en.wikipedia.org/wiki/File:Sigma_bond.svg.
“File:Tetrahedral-3D-Balls.png,” August 17, 2013. http://en.wikipedia.org/wiki/File:Tetrahedral-3D-balls.png.
“File:Trigonal-3D-Balls.png,” August 17, 2013. http://en.wikipedia.org/wiki/File:Trigonal-3D-balls.png.
“File:Trigonal-Bipyramidal-3D-Balls.png,” August 18, 2013. http://en.wikipedia.org/wiki/File:Trigonal-bipyramidal-3D-balls.png.
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