COVALENT BONDING
Hybridization and the Localized Electron Model
number of
electron pairs
hybrid
orbitals
orbital geometry
angles
2
sp
linear
180°
3
sp2
trigonal planar
120°
4
sp3
tetrahedral
109.5°
5
sp3d
trigonal bipyramidal
120°, 90°
octahedral
90°
6
3 2
sp d
1.
Describe the hybridization around the central atom in (a) CF4, (b) SbCl6, and (c) AsF5
2.
What are the hybridization and approximate bond angles for the N, C, and O atoms in alanine, an
amino acid, whose Lewis structure is:
3.
Methylcyanoacrylate is the active ingredient in "super glues." Its Lewis structure is:
(a) How many sigma bonds are in the molecule?
(b) How many pi bonds are in the molecule?
(c) What is the hybridization of the carbon atom bonded to nitrogen?
(d) What is the hybridization of the carbon atom bonded to oxygen?
(e) What is the hybridization of the double-bonded oxygen?
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4.
Aspirin, or acetylsalicylic acid, has the formula C9H8O4 and the skeleton structure:
Complete the Lewis structure and give the number of σ bonds and π bonds in aspirin.
The Molecular Orbital Model
MO diagram from H2 to N2
MO diagram for O2, F2
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Molecular orbital electron configurations, bond orders, and magnetism
species
electron configurations
bond order
magnetism
H2
(σ1s)2
1
diamagnetic
Li2
(σ1s)2(σ*1s)2(σ2s)2
1
diamagnetic
B2
(σ1s)2(σ*1s)2(σ2s)2(σ*2s)2(π2p)2
1
paramagnetic
C2
(σ1s)2(σ*1s)2(σ2s)2(σ*2s)2(π2p)4
2
diamagnetic
N2
(σ1s)2(σ*1s)2(σ2s)2(σ*2s)2(π2p)4(σ2p)2
3
diamagnetic
O2
(σ1s)2(σ*1s)2(σ2s)2(σ*2s)2(σ2p)2(π2p)4(π*2p)2
2
paramagnetic
F2
(σ1s)2(σ*1s)2(σ2s)2(σ*2s)2(σ2p)2(π2p)4(π*2p)4
1
diamagnetic
5.
Draw the molecular orbital diagram, including the electrons, and write the electron configuration
of He22+. Give the bond order and the number of unpaired electrons, if any. Is this a stable species?
6.
Predict which species in each pair has the stronger bond.
(a) B2 or B2−
(b) C2− or C2+
(c) O22+ or O2
7.
Is NO+ diamagnetic or paramagnetic?
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