Name:
Date:
AP Chemistry
Word Problem Wednesday: Molecular Geometry
Note: The following are problems taken directly from past AP Exams
Rules:
-Your team starts with a total of 110 points
-Each hint from Sharar is -5 points
-Talking to another group is -5 points
-You may use any resources you want (notes, videos, textbook, online resources)
-This is worth a problem set (out of 100 points)
-You have 20 minutes per problem
-Show your work/explanation on a separate sheet of paper and attach it. One copy per group.
Group Members:
Score:
Question #1
1. Answer the following questions using principles of chemical bonding and molecular
structure
a. Consider the carbon dioxide molecule, CO2, and the carbonate ion, CO32-.
i. Draw the complete Lewis electron structure for each species
ii. Which molecule would have a larger bond angle around its central atom?
Explain.
iii. Explain why the carbon oxygen bond length in carbonate is greater than
the carbon oxygen bond length in CO2
b. Consider the molecules CF4 and SF4.
i. Draw the complete Lewis electron structure for each molecule
ii. In terms of molecular geometry, account for the fact that the CF 4
molecule is nonpolar, whereas the SF4 molecule is polar
Question #2
2. Answer the following questions using principles of chemical bonding and molecular
structure
a. Draw the Lewis structures for PF3 and PF5 and predict the molecular geometry of
each.
b. Is the PF3 molecule polar or is it nonpolar? Explain.
c. Use Lewis structures and resonance to explain why the carbon-oxygen bonds in
the oxalate ion (C2O42-) are all equal in length.
d. Determine the bond angle around each carbon in oxalate. Explain your answer.
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