Week 6
Recitation Section
1. Lewis Dot: Write the Lewis dot structures, show formal charge and resonance
structures:
a. N2, SF4, NO, SF6, CO, NO-, BF4b. SH2, BF4-, NO3-, NO3c. SO3, ICl3, SeF6, OF2, AsO43-, NCS-, SCO–, N3–
d. CH3COO–, SCN-,, SO2, SO42–, C6H6,
e. H2C2, H4C2, H2CO2H, H2COH
f. H8C4, H12C6 , C5H5-, C7H12
2. Write Resonance and Lewis Dot structures for: NO2-, NO3-, SO2, SO3
3. VSEPR:
4. Define Steric number:
5. Fill in the table below:
Steric #
6
5
4
3
2
geometry
example
SF6
PF5
CH4, SO42SO3
BeH2, CO2
linear
6. Predict the shapes of:
CH4, NH3, H2O,
why does the angle change
H4C2 SO3, SO2, O3
7. Fill in the table:
Steric #
Geometry
3
3
4
4
4
5
5
5
5
6
Oh
6
6
6
6
8. What is the shape of:
a. IF4-,
Lone Pairs
0
1
0
1
2
0
1
2
3
0
1
2
3
4
PF3,
Shape
Oh
XeF2, SO2,
example
SO3
SO2
CH4, SO42NH3
H2 O
PF5
SF4
CLF3
XeF2
SF6
IF5
XeF4
b.
c.
d.
e.
f.
SO42-,
SO3,
CS2
ClO2
SF2,
PF5,
ICl3,
SiH 4
H3CCO2H
SeF6,
BF3, CS2,
CBr4, SiH4,
SF2
H2CCCH2
PF3
9. What is the shape around each of the C atoms in H3CCOOH, H2CCH2, HCCCH3
10. Draw the Bonding and antibonding orbitals for H2
11. Why is the bond in Li2 weaker then H2
12. Draw the MO diagram for B2, C2 N2 O2 F2
13. What is the MO for O2 different than N2
14.
15. What orbitals participate in the bonding in HF and HCl. Why is the HCl bond
weaker.
16. Is H2- magnetic?
1. Lewis Dot: Write the Lewis dot structures, show formal charge and resonance
structures:
a. N2, SF4, NO, SF6, CO, NO-, BF4F
F
Si
B–
F
F
F
F
:N:::N:,
b. SH2, BF4-, NO3-,
N
, :–C-::O:+, –N=O,
O
F
F
F
H
S
F
H
B-
-O
F
N+
O
O-
F
3-
-
–
c. SO3, ICl3, SeF6, OF2, PO4 , NCS , SCO , N3
S2+
O
S+
O
O-
N+
O
O-
O-
S
O-
N2–
-,
-S
O-
+
2–
C
d. CH3COO , SCN , SO2, SO4 , C6H6
e. H2C2, H4C2, H2CO2H, H2COH
Cl
-O
O
As
O
,
N
S
C
-O
As
O
O-
O-
5 more
3 more
C
I
Cl
O-
+S
O-
O
O-O
N+
O
2 more
S
O
O
Cl
2 more
-
O-
–
O
O
O-
N-
C
C
C
C
C
C
C
C
C
C
f.
,
c
C
C-
C
C
,
(only C shown)
2. Write Resonance and Lewis Dot structures for: NO2-, NO3-, SO2, SO3
3. VSEPR:
4. Define Steric number:
5. Fill in the table below:
Steric #
6
5
4
3
2
geometry
Oh
Sq pyramidal
Td
Trigonal planar
linear
example
SF6
PF5
CH4, SO42SO3
BeH2, CO2
6. Predict the shapes of:
CH4, NH3, H2O,
why does the angle change
Td, trigonal pyramidal, bent; angle 109.5, 107, 104
H4C2 SO3, SO2, O3
7. Fill in the table:
Steric #
Geometry
3
trigonal planar
3
trigonal planar
4
Td
4
Td
4
Td
5
trigonal
bipyrimidal
Lone Pairs
0
1
0
1
2
0
Shape
trigonal planar
bent angle<120
Td
sq pyrimide
bent angle <107
trigonal
bipyrimidal
example
SO3
SO2
CH4, SO42NH3
H2 O
PF5
5
5
5
6
6
6
6
6
trigonal
bipyrimidal
trigonal
bipyrimidal
trigonal
bipyrimidal
Oh
Oh
Oh
Oh
Oh
1
saw horse
SF4
2
T shape
CLF3
3
linear
XeF2
0
1
2
3
4
Oh
sq pyrimide
sq planar
T shape
linear
SF6
IF5
XeF4
8. What is the shape of:
g. IF4-, sq planar
PF3, trig. Pyr. XeF2, linear SO2 bent angle  115,
2h. SO4 , Td
PF5,trig. bipyr BF3, trig plan CS2, linear
i. SO3, trig planar ICl3, trig plan CBr4, Td
SiH4 Td
j. SiH 4 Td
SF2 bent
k. ClO2 bent
H3CCO2H Td (left C) trig plan (right C)
H2CCCH2 trig
planar, linear, trig planar
l. SF2, bent
SeF6, Oh
PF3 trig pyr
9. What is the shape around each of the C atoms in H3CCOOH, H2CCH2, HCCCH3
10. Draw the Bonding and antibonding orbitals for H2
- H
bonding
-
- H
- H
antibonding
11. Why is the bond in Li2 weaker then H2
2s more diffuse than 1s so overlap is worse
12. What orbitals participate in the bonding in HF and HCl. Why is the HCl bond
weaker.
In HF it is 1s and 2p orbitals while in HCl it is 1s and 3p the over lap of 3p with 1s worse
13. Is H2- magnetic?
No spins are paired.