CK-12-Chemistry Intermediate

9.2. Molecular Geometry http://www.ck12.org

Lesson Review Questions

Reviewing Concepts

1. Why is it important to know the geometry or shape of a molecule?


2. What is the difference between electron domain geometry and molecular geometry? Use an example.


3. In terms of its effect on molecular geometry, how does the repulsion from a lone pair of electrons compare to
   the repulsion from a bonding pair of electrons?


4. How many atoms are directly bonded to the central atom in molecules that have the following molecular
   geometries?
   a. trigonal bipyramidal
   b. tetrahedral
   c. octahedral
   d. bent
   e. trigonal pyramidal
   f. square planar


5. Explain why the bond angle in an H 2 O molecule is smaller than the bond angle in an NH 3 molecule.


6. SF 4 and CH 4 have similar molecular formulas. Why does the SF 4 molecule adopt a seesaw geometry, while
   the CH 4 molecule is tetrahedral?

Problems

7. Using the VSEPR method, predict the molecular geometries of the following molecules:
   a. SF 2
   b. PBr 3
   c. AlCl 3
   d. TeCl 4
   e. HCN


8. Predict the molecular geometries of the following ions:
   a. NO 3 −
   b. ICl 2 −
   c. ClO 3 −
   d. PO 43 −
   e. SeCl 3 −


9. Predict the H-As-H bond angle in AsH 3. Predict the H-B-H bond angle in BH 3. Explain the difference.


10. What are the molecular geometry and the bond angle for XeF 2?


11. In the XeOF 4 molecule, the central xenon atom has a double bond to the oxygen atom and single bonds to the
    four fluorine atoms. Predict the geometry of this molecule.

Further Reading / Supplemental Links

• Jeremy K. Burdett,MolecularShapes:TheoreticalModelsofInorganicStereochemistry, John Wiley Sons,
  Inc., 1980.


• Chemistry,Structures&3DMolecules (http://www.3dchem.com/#


• ValenceShellElectronPairRepulsionVSEPR (http://www.meta-synthesis.com/webbook/45_vsepr/VSEPR.html