Title: Valence%20shell%20electron%20pair%20repulsion%20(VSEPR)%20model:
1Valence 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
210.1
3VSEPR
AB2
2
0
linear
linear
AB3
3
0
10.1
410.1
5VSEPR
AB2
2
0
linear
linear
AB4
4
0
10.1
610.1
7VSEPR
AB2
2
0
linear
linear
AB4
4
0
tetrahedral
tetrahedral
AB5
5
0
10.1
810.1
9VSEPR
AB2
2
0
linear
linear
AB4
4
0
tetrahedral
tetrahedral
AB6
6
0
10.1
1010.1
1110.1
12(No Transcript)
13VSEPR
trigonal planar
trigonal planar
AB3
3
0
AB2E
2
1
10.1
14VSEPR
AB4
4
0
tetrahedral
tetrahedral
AB3E
3
1
10.1
15VSEPR
AB4
4
0
tetrahedral
tetrahedral
AB2E2
2
2
10.1
16VSEPR
trigonal bipyramidal
trigonal bipyramidal
AB5
5
0
AB4E
4
1
10.1
17VSEPR
trigonal bipyramidal
trigonal bipyramidal
AB5
5
0
AB3E2
3
2
10.1
18VSEPR
trigonal bipyramidal
trigonal bipyramidal
AB5
5
0
AB2E3
2
3
10.1
19VSEPR
AB5E
5
1
10.1
20VSEPR
AB4E2
4
2
10.1
2110.1
22Predicting Molecular Geometry
- Draw Lewis structure for molecule.
- Count number of lone pairs on the central atom
and number of atoms bonded to the central atom. - Use VSEPR to predict the geometry of the molecule.
AB4E
AB2E
distorted tetrahedron
bent
10.1
23sp3
sp2
24Dipole 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
2510.2
2610.2
27dipole moment polar molecule
dipole moment polar molecule
no dipole moment nonpolar molecule
no dipole moment nonpolar molecule
10.2
2810.2
2910.2
3010.2
31Sharing of two electrons between the two atoms.
Valence bond theory bonds are formed by sharing
of e- from overlapping atomic orbitals.
10.3
32Change in electron density as two hydrogen atoms
approach each other.
10.3
33Hybridization 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
34Formation of sp3 Hybrid Orbitals
10.4
3510.4
3610.4
37Formation of sp Hybrid Orbitals
10.4
38Formation of sp2 Hybrid Orbitals
10.4
39- Draw the Lewis structure of the molecule.
- 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
4010.4
4110.5
4210.5
4310.5
4410.5
4510.5
4610.5
47C 3 bonded atoms, 0 lone pairs C sp2
10.5
48Sigma (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
49Delocalized molecular orbitals are not confined
between two adjacent bonding atoms, but actually
extend over three or more atoms.
10.8
50Electron density above and below the plane of the
benzene molecule.
10.8