Valence%20shell%20electron%20pair%20repulsion%20(VSEPR)%20model:

1
Valence shell electron pair repulsion (VSEPR)
model
Predict the geometry of the molecule from the
electrostatic repulsions between the electron
(bonding and nonbonding) pairs.
AB2
2
0
10.1
2
10.1
3
VSEPR
AB2
2
0
linear
linear
AB3
3
0
10.1
4
10.1
5
VSEPR
AB2
2
0
linear
linear
AB4
4
0
10.1
6
10.1
7
VSEPR
AB2
2
0
linear
linear
AB4
4
0
tetrahedral
tetrahedral
AB5
5
0
10.1
8
10.1
9
VSEPR
AB2
2
0
linear
linear
AB4
4
0
tetrahedral
tetrahedral
AB6
6
0
10.1
10
10.1
11
10.1
12
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VSEPR
trigonal planar
trigonal planar
AB3
3
0
AB2E
2
1
10.1
14
VSEPR
AB4
4
0
tetrahedral
tetrahedral
AB3E
3
1
10.1
15
VSEPR
AB4
4
0
tetrahedral
tetrahedral
AB2E2
2
2
10.1
16
VSEPR
trigonal bipyramidal
trigonal bipyramidal
AB5
5
0
AB4E
4
1
10.1
17
VSEPR
trigonal bipyramidal
trigonal bipyramidal
AB5
5
0
AB3E2
3
2
10.1
18
VSEPR
trigonal bipyramidal
trigonal bipyramidal
AB5
5
0
AB2E3
2
3
10.1
19
VSEPR
AB5E
5
1
10.1
20
VSEPR
AB4E2
4
2
10.1
21
10.1
22
Predicting Molecular Geometry

1. Draw Lewis structure for molecule.
2. Count number of lone pairs on the central atom
   and number of atoms bonded to the central atom.
3. Use VSEPR to predict the geometry of the molecule.

AB4E
AB2E
distorted tetrahedron
bent
10.1
23
sp3
sp2
24
Dipole Moments and Polar Molecules
electron rich region
electron poor region
m Q x r
Q is the charge
r is the distance between charges
1 D 3.36 x 10-30 C m
10.2
25
10.2
26
10.2
27
dipole moment polar molecule
dipole moment polar molecule
no dipole moment nonpolar molecule
no dipole moment nonpolar molecule
10.2
28
10.2
29
10.2
30
10.2
31
Sharing of two electrons between the two atoms.
Valence bond theory bonds are formed by sharing
of e- from overlapping atomic orbitals.
10.3
32
Change in electron density as two hydrogen atoms
approach each other.
10.3
33
Hybridization mixing of two or more atomic
orbitals to form a new set of hybrid orbitals.

• Mix at least 2 nonequivalent atomic orbitals
  (e.g. s and p). Hybrid orbitals have very
  different shape from original atomic orbitals.
• Number of hybrid orbitals is equal to number of
  pure atomic orbitals used in the hybridization
  process.
• Covalent bonds are formed by
• Overlap of hybrid orbitals with atomic orbitals
• Overlap of hybrid orbitals with other hybrid
  orbitals

10.4
34
Formation of sp3 Hybrid Orbitals
10.4
35
10.4
36
10.4
37
Formation of sp Hybrid Orbitals
10.4
38
Formation of sp2 Hybrid Orbitals
10.4
39

1. Draw the Lewis structure of the molecule.
2. Count the number of lone pairs AND the number of
   atoms bonded to the central atom

of Lone Pairs of Bonded Atoms
Hybridization
Examples
2
sp
BeCl2
3
sp2
BF3
4
sp3
CH4, NH3, H2O
5
sp3d
PCl5
6
sp3d2
SF6
10.4
40
10.4
41
10.5
42
10.5
43
10.5
44
10.5
45
10.5
46
10.5
47
C 3 bonded atoms, 0 lone pairs C sp2
10.5
48
Sigma (s) and Pi Bonds (p)
1 sigma bond
Single bond
1 sigma bond and 1 pi bond
Double bond
Triple bond
1 sigma bond and 2 pi bonds
s bonds 6
1 7
p bonds 1
10.5
49
Delocalized molecular orbitals are not confined
between two adjacent bonding atoms, but actually
extend over three or more atoms.
10.8
50
Electron density above and below the plane of the
benzene molecule.
10.8