CHM134 General Chemistry I
Exam 4, Spring 2011
Name
1. Draw a reasonable Lewis Dot Structure for each of these species. Show all valence
electrons. None of these require you to violate the octet rule. (16 points)
CO2
NH3
HCN
HOOH
2. Draw a reasonable Lewis Dot Structure for each of these species. Show all valence
electrons. Each of these requires you to violate the octet rule. (12 points)
ClF3
-
SF5
BeF2
3. Draw a Lewis Dot Structure for the [IO2]- ion and include any resonance if necessary. Make
sure your structure is ideal in terms of formal charges (Oxygen has a greater electronegativity
than Iodine). (10 points)
4. Assign formal charges to the elements in each of the structures below. (9 points)
A
B
C
Formal Charge
C
N
O
5. (3 pts) The best Lewis structure for CNO – is which one above?
A B C
6. Complete the chemical structure below by adding any necessary lone pairs and multiple
bonds. Next, identify the type of hybridization present at each Carbon and at each Oxygen
atoms. (10 points)
H
Cl
C
H
H
C
H
C
O
H
O
C
C
O
H
Draw arrows to each Carbon and each Oxygen and indicate hybridization.
H
7. Based on the Lewis Structures provided, given the electron pair geometry, provide a sketch
of the species along with idealized bond angles, name the molecular geometry, and identify
the type of orbital hybridization present on the central atom of the species. (20 points)
Molecule
NH3
O3
O
O
IF4+
IF5
O
Lewis
Structure
O
O
O
Electron pair
geometry
Sketch
(with angles)
VSEPR
Geometry
Hybridization
on central
atom
8. In the following list, circle the polar molecules (8 points):
NH3
BCl3
SF4
CH4
XeF4
XeF2
SCl2
CO2
Use the included molecular orbital diagram to help answer the remaining questions. (2pts each)
9. According to molecular orbital theory, what is the bond order in the C2 molecule? _____
10. Circle one: MO theory predicts that the C2 molecule is diamagnetic or paramagnetic?
11. According to molecular orbital theory, what is the bond order in the C22- ion? _____
12. Circle one: MO theory predicts that the C22- ion is diamagnetic or paramagnetic?
13. Circle one: According to molecular orbital theory, which one of these species has the shortest
bond length (strongest bond)?
N22+
N2
N22-
14. According to molecular orbital theory, circle any that will be paramagnetic:
N22+
N2
N22-
---------------------------------------------------------------------------------------------------scratch area for MO questions