Review for final

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Review for final F March 14 1 pm ES 413 Room S
March 16 6 pm BI 234
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Draw Lewis dot structures for the halogens.
Notice that these all follow the octet rule!
Try oxygen and nitrogen.
These also follow the octet rule!
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Bond Lengths and Covalent Radius
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Figure 9.14 The HCl molecule.
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The Charge Density of LiF
Fig. 9.20
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Figure 9.12 Molecular model of nitro-glycerin.
What is the formula for this compound?
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Rules for drawing Lewis structures
1. Count up all the valence electrons
2. Arrange the atoms in a skeleton
3. Have all atoms develop octets (except those
around He)
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Make some Lewis Dot Structures with other
elements
SiH4
H2O
NH3
CH2O
C2H6
C2H6O
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Figure 9.9 Model of CHI3Courtesy of Frank Cox.
CH3I
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Make some Lewis Dot Structures with other
elements
CH4
H2O
NH3
CH2O
C2H6
C2H6O
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Look at all these structures and make some
bonding rules
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Rules for drawing Lewis structures
1. Count up all the valence electrons
2. Arrange the atoms in a skeleton
3. Have all atoms develop octets (except those
around He)
4. Satisfy bonding preferences!
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A model of ethylene.
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A model of acetylene.
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A model of COCl2.
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A model of SCl2.
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Figure 9.16 Delocalized bonding in sodium metal.
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Model of CO32-
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The Relation of Bond Order,Bond Length and Bond
Energy
Bond Bond Order Average Bond
Average Bond
Length (pm)
Energy (kJ/mol)
C O 1
143 358 C
O 2
123 745 C O
3 113
1070 C C
1 154
347 C C 2
134
614 C C 3
121
839 N N 1
146
160 N N 2
122 418 N
N 3
110 945
Table 9.4
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Conceptual Problem 9.103
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Fig. 9.14
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Figure 9.15 Electronegatives of the elements.
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The Periodic Table of the Elements
2.1
He
0.9
1.5
2.0
2.5
3.0
3.5
4.0
Ne
Electronegativity
0.9
1.2
Ar
1.5
1.8
2.1
2.5
3.0
0.8
1.0
1.3
1.5
1.6
1.6
1.5
1.8
1.8
1.8
1.9
1.6
1.6
1.8
2.0
2.4
2.8
Kr
0.8
1.0
1.2
1.4
1.6
1.8
1.9
2.2
2.2
2.2
1.9
1.7
Xe
2.5
2.1
1.9
1.8
1.7
0.7
0.9
1.1
1.5
1.7
1.9
2.2
2.2
2.4
1.9
Rn
2.2
2.0
1.9
1.8
1.8
1.3
2.2
0.7
0.9
1.1
Ce Pr Nd Pm
Yb Lu
1.1
1.1
1.1
1.1
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.3
1.3
1.5
1.7
1.3
1.3
1.3
1.3 1.3
1.3
1.3
1.3
1.5
1.3
Th Pa U Np
No Lr
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Fig. 9.16
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Fig. 9.17
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Determining Bond Polarity from
Electronegativity Values
Problem (a)Indicate the polarity of the
following bonds with a polarity arrow O -
H, O - Cl, C - N, P - N, N - S, C - Br, As - S
(b) rank those bonds in order of increasing
polarity. Plan (a) We use Fig. 9.16 to find the
EN values, and point the arrow toward the
negative end. (b) Use the EN values. Solution
a) the EN of O 3.5 and of H 2.1 O - H
the EN of O 3.5 and of Cl 3.0 O
- Cl the EN of C 2.5 and of P 2.1
C - P the EN of P
2.1 and of N 3.0 P - N the EN of N
3.0 and of S 2.1 N - S the
EN of C 2.5 and of Br 2.8
C - Br the EN of As 2.0 and of O
3.5 As - O
b) C - Br lt C - P lt O - Cl lt P - N lt N - S lt O -
H lt As - O 0.3 lt 0.4 lt 0.5 lt
0.9 lt 0.9 lt 1.4 lt 1.5
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Fig. 9.18
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Percent Ionic Character as a Function
ofElectronegativity Difference (?En)
Fig. 9.19
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The Charge Density of LiF
Fig. 9.20