Chemical Bonding II: Molecular Geometry and Hybridization of Atomic Orbitals - PowerPoint PPT Presentation

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Chemical Bonding II: Molecular Geometry and Hybridization of Atomic Orbitals

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Valence shell electron pair repulsion (VSEPR) model: Predict the geometry of the molecule from ... Mix at least 2 nonequivalent atomic orbitals (e.g. s and p) ... – PowerPoint PPT presentation

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Title: Chemical Bonding II: Molecular Geometry and Hybridization of Atomic Orbitals


1
Chemical Bonding IIMolecular Geometry and
Hybridization of Atomic Orbitals
Chapter 10
2
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
3
0 lone pairs on central atom
4
VSEPR
AB2
2
0
linear
linear
AB3
3
0
5
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6
VSEPR
AB2
2
0
linear
linear
AB4
4
0
7
(No Transcript)
8
VSEPR
AB2
2
0
linear
linear
AB4
4
0
tetrahedral
tetrahedral
AB5
5
0
9
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10
VSEPR
AB2
2
0
linear
linear
AB4
4
0
tetrahedral
tetrahedral
AB6
6
0
10.1
11
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12
(No Transcript)
13
(No Transcript)
14
VSEPR
trigonal planar
trigonal planar
AB3
3
0
AB2E
2
1
15
VSEPR
AB4
4
0
tetrahedral
tetrahedral
AB3E
3
1
16
VSEPR
AB4
4
0
tetrahedral
tetrahedral
AB2E2
2
2
17
VSEPR
trigonal bipyramidal
trigonal bipyramidal
AB5
5
0
AB4E
4
1
18
VSEPR
trigonal bipyramidal
trigonal bipyramidal
AB5
5
0
AB3E2
3
2
19
VSEPR
trigonal bipyramidal
trigonal bipyramidal
AB5
5
0
AB2E3
2
3
20
VSEPR
AB5E
5
1
21
VSEPR
AB4E2
4
2
22
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23
Predicting 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.

What are the molecular geometries of SO2 and SF4?
24
Dipole Moments and Polar Molecules
electron rich region
electron poor region
25
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26
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27
Which of the following molecules have a dipole
moment? H2O, CO2, SO2, and CH4
28
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

29
How do I predict the hybridization of the central
atom?
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
30
Sigma bond (s) electron density between the 2
atoms
Pi bond (p) electron density above and below
plane of nuclei of the bonding atoms
31
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32
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33
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34
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
How many s and p bonds are in the acetic
acid (vinegar) molecule CH3COOH?
35
Delocalized molecular orbitals are not confined
between two adjacent bonding atoms, but actually
extend over three or more atoms.
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