Chapter 9: VSEPR

Building Molecular Models

Part I: Use your molecular modeling kits.

You will use 4 sheets of white paper for this lab (front and back sides).  Fold 3 sheets of your blank white paper into 4 rectangles like this. Label each with a number and the chemical formula which corresponds to the molecule listed on the list below.

(portrait-view, NOT landscape)

For each structure below on your paper, include the following:

• Draw the structural formula (Lewis structures) - be sure to include all non-bonding e^- pairs as well.
• Follow these 4 steps.
  • Write out the VSEPR arithmetic - show this on your paper.
  • VSEPR: Make the molecule using the kits provided. 
  • Draw what the structure looks like in 3-D - use the drawing techniques you have learned.  LABEL the atoms with the atom symbol.
  • Name the molecular shape after you've made the molecule.  Then, take the molecule apart and go on to the next one.

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1.           N₂  (REMEMBER, if there is "no center", you can't use VSEPR. 
              But, in this case, you surely can draw out the molecular shape, can't you?)
2.           HClO  (in this case, the oxygen is the central atom)
3.           PF₃
4.           CF₄

5.           CO₂
6.           CH₃Cl
7.           CCl₄
8.           CH₃OH (name EACH center - the carbon is one center, the oxygen is the other center)

9.          HF  (no central atom....so, what shape MUST this be?)
10.        C₂H₂ (name each center - one carbon is one center, the other carbon is the other center)
11.        SiO₂
12.        CH₄

13.        H₂O
14.        Cl₂
15.        HBr  (no central atom....so, what shape MUST this be?)
16.        H₂O₂

For these,

• Draw the STRUCTURAL FORMULAS for each molecule so you can see "what atom is connected to what." 
• Then, using your MODELING KITS,  MAKE THE MOLECULE.
• Then, DRAW what you see using the graphing techniques you were taught.
• Label EACH ATOM.
• Label each center and then name the shape at each center.

17.        CH₃CH₂OH (3 centers)

18.        CH₃COOH (3 centers)

19.        CHCCH₂CHCHCH₃ (6 centers)

20.        CH₃COCHCHCH₂NH₂ (6 centers)

Part II: Use a brand new page of white blank paper.  As you did above, divide the paper into 4 sections.  

For the following molecules, use VSEPR and draw the 3-D molecular shapes and then name the molecular shape (don't use the kits for these):

21.         SF₆
22.         XeF₄
23.         BrF₅
24.         PCl₅

ANSWER THIS QUESTION ON YOUR PAPER AT THE BOTTOM OF THE PAGE: Do any of the 4 structures listed above follow the octet rule?

Part III: Use a brand new page of white blank paper.  Draw all the structural isomers for C₆H₁₄.

ANSWER THIS QUESTION ON YOUR PAPER AT THE BOTTOM OF THE PAGE: How many isomers are there?