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8/8/2019 04. Hybridization 2010
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1CHEM 212
Nicolas Moitessier
Chemical BondsChemical bonds
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Information
Introduction: What is Organic Chemistry ?
Structures: Ch. 1.3
Alkanes: Ch. 2.1-2.3
Functional groups: Ch. 2.5-2.13
Chemical Bonding & Lewis Structures: Ch. 1.4-1.6
Formal Charges and Resonance: Ch. 1.7-1.8
VSEPR Theory Ch. 1.16
Hybridization Ch. 1.11-1.15
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Chemical Bonding
Bonds can be
Covalent. Ex.: CH4
Atoms achieve octets by sharing of valence electrons
Ionic Ex. NaCl, LiFOctet rule: Lithium loses an electron and becomes positively charged
Fluoride gains an electron and becomes negatively chargedThe charged lithium and fluoride form a strong ionic bond
C
H
H H
HC
H
HH
H
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Valence Bond Theory
The covalent bond results from an overlap of atomic
orbitals containing one unpaired electron each Pauling (Nobel in Chemistry 1954 in Peace 1962)
Aufbau orbitals are filled so that those of lowest energy are filled first
Pauli a maximum of two electrons with paired spins may be placed in each
orbital
Hund With orbitals of equal energy, one electron (unpaired spins) is added to
each until each contains one electron
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The Covalent Bond - Pauling
Sharing of unpaired electrons
H H
1s 1s
1s 1s
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The Covalent Bond - Pauling
Shairing of unpaired electrons
H H
1s 1s
σ bond
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H2
1s + 1s = σ
H H H2
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F2
p-p Overlap
F1s 2s 2p
F
1s 2s 2p
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He2
?
No unpaired electrons
This molecule cannot exist
He He
1s 1s
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HF?
Unpaired electrons
s-p overlap
F
1s 2s 2p
H
1s
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HF
Fluoride is more electronegative than H:
polarized bond
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Single bonds
Carbon atom
4 sp3 electrons
C
1s 2s 2p
C
1s 2s 2p
H
1s
jump
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Hybridization
2s + 2px+ 2py+ 2pz= 4 sp3 e-
C
1s 2s 2p
sp3
Hybri dization
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Methane
Hybridization
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Methane
Bond formation
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Methane
Lewis Structure
Geometry (VSEPR)
Bonding (Valence bond theory): 4
equivalent σ bonds
C H
H
H
H
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Multiple bonds
Ethylene
Lewis structure
VSEPR: 2 trigonal planar carbons
Valence bond theory: 1σ and 1π
C C
H
H
H
H
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Hybridization
C
2s 2p
sp2 p
C
2s 2p
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Ethylene
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Ethylene
sp2 p
3 σ bonds 1 π bond
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π bond
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Triple bond
Acetylene (ethyne)
Lewis structure
VSEPR: 2 linear carbons
Valence bond theory: 1σ and 2π
C C HH
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Triple Bonds
C
2s 2p
sp p
C
2s 2p
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Acetylene
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Acetylene
sp p
sp p
H
s
H
s
σ bond 2 π bonds
σ bond
σ bond
C C HH C C HH C C HH C CC C HH C CC C HH C C
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The electron configuration shown
below represents
1 2 3 4 5
0% 0% 0%0%0%
1s 2sp3 2sp3 2sp3 2sp3
1. the ground state of boron.
2. the sp3 hybridized state ofcarbon
3. the sp3 hybridized state ofnitrogen
4. the ground state of carbon.5. an excited state of carbon.
