Download CHM1045 - Michael Blaber

CHM1045
Fall 1998
Dr. Michael Blaber
Name_______________________________
SS#________________________________
Exam #3 100 points total
Fri November 13th 1998
1. Using Lewis dot structures, indicate the movement of electrons during the formation of
the ionic compound Calcium Oxide (CaO) from Calcium (Ca) and Oxygen (O) (5 points)
2. If the atomic radius of the Calcium ion in question #1 is 0.99 x 10-10 m and the atomic
radius of the Oxygen ion is 1.40 x 10-10 m what will be the magnitude of the attractive
potential energy between the two charged ions in CaO ? (k = 8.99 x 109 J m /C2) (5
points)
3. Provide an example of four ions in an isoelectronic series with 36 electrons (8 points)
4. Which of the following ions is the largest? Ca2+, K+, Cl-, S2- (5 points)
5. Draw the Lewis structure of the Sulfate (SO42-) ion (5 points)
6. What is the formal charge on the Sulfur atom in the sulfate ion? What is the formal
charge on an Oxygen atom in the sulfate ion? (5 points)
7. Draw the Lewis structure for SeO3 (5 points)
8. Which of the following Lewis structures of phosphate ion (PO43-) is the most likely? (5
points)
9. Given the bond energies on the last page of the exam, estimate the enthalpy associated
with the combustion of methane (CH4). (8 points)
10. What is the oxidation number for the Carbon and Oxygen atoms in the carbonate ion
(CO32-)? (4 points)
11. Name the following molecular geometries for typical ABn type molecules: (8 points)
12. Draw a Lewis structure for iodine pentafluoride (IF5). What is the valence electron pair
geometry of the Iodine and molecular geometry of the molecule? (5 points)
13. Give the approximate values for the bond angles indicated in the following molecule: (6
points)
1
O
H
C
3
H
O
C
2
H
H
14. Give the valence electron geometry, expected hybrid orbitals, and molecular geometry
for the indicated atoms in the following structure: (9 points)
O
H
C
H
O
C
H
H
1
2
3
15. For each the atoms indicated in the following structure, draw a valence electron orbital
diagram (8 points)
4
O
H
C
H
O
C
H
H
1
2
3
16. For an ABn type of molecule, indicate which of the following molecular geometries
would be result in a polar molecule and which would be non-polar: (9 points)
Trigonal planar
Tetrahedral
Trigonal pyramidal
Bent
T-shape
Linear
Square planar
Octahedral
Trigonal bipyramidal
Exam III Appendix
Electron charge = 1.602 x 10
-19
C
Bond energies (kJ/mol)
C-H
O=O
C=O
O-O
C-O
O-H
413
495
799
146
358
463