1. With your models, construct the molecule methane. After you put the model together, answer the questions below on your answer sheet. a.
With the model sitting so that three hydrogens are on the desk, examine the structure. Move the model so that a different set of three hydrogens are on the desk. Is there any difference between how the model looks before and after moving it? b.
Does the term “equivalent” apply to the hydrogens in methane? c.
Tilt the model so that only two hydrogens are in contact with the desk. Draw a three dimensional picture of the model. d.
Using a protractor, measure the H-C-H bond angle.
2. Replace one of the hydrogens of the methane model with a chlorine. Draw a three dimensional picture of your model.
3. Now replace a second hydrogen with another chlorine. The new molecule is dichloromethane, CH
2
Cl
2
.
Examine the model as you twist and turn it in space. Then answer the questions below: a.
Are the projections below isomers of the molecule CH
2
Cl
2
, or representations of the same molecule seen from different angles? b.
Based on your answer to 3a, is the molecule always polar, sometimes polar or never polar?
4. Construct the model for ethane. a. Draw the 3D model for the ethane molecule. b. Are all the hydrogens attached to the carbon atoms equivalent? c. Replace any hydrogen atom with chlorine. Does it matter where the chlorine is attached? d. Rotate the carbon containing the chlorine. How does this affect the molecule?
5. Now create a molecule of dichloroethane by removing another hydrogen from the same carbon you placed the first chlorine on. a. Name this compound. b. Build, draw and name a structural isomer for this compound. c. With the second isomer, rotate the chlorine around one of the carbons. How does this change the molecule? d. Is this molecule never polar, always polar or sometimes polar? Explain.

6. Take apart the dichloroethane molecule. Take away two hydrogens to form 1,2dichloroethene. Use two of the flexible longer bonds to make the double bond. a. Draw the compound you have built. b. Try rotating the carbon to change the alignment of the chlorine atoms. Can you twist it? Comment on the flexibility of the double bond. c. Use your protractor to measure the bond angle of for dichloroethene.
7. For each of the following molecules, make a model using the kit provided. Then (a) sketch an accurate 3-D model, (b) name the compound and (c) write the condensed formula on the answer sheet. Then answer the questions below.
1a. 3a.
H
3
C CH
3
H
3
C
CH
3
H
3
C
2a. 4a.
CH
3
CH
3
H
3
C CH
3
CH
3 a.
Which of the molecules that you have built are structural isomers of each other? b.
How are these molecules alike? How are they different? c.
Based on their structure, in what ways would you expect them to behave similarly? In what ways would you expect them to behave differently? (think about properties such as density, melting point, solubility in water, and reactivity. d.
Molecule 4a is a cyclic compound. Comment on the flexibility of the carbon chain in a cyclic compound vs. a noncyclic compound. e.
Use a protractor to measure the bond angle of the carbons in the cyclobutane ring.
8. Draw Lewis or Bond-Line diagrams for each molecule below. a.
2,3 dimethyl pentane b.
1-ethyl-2-methyl cyclohexane c.
3-bromo-4-diethyl heptane d.
3-isopropylpentane e.
C(CH
3
)
3
CH
2
Cl f.
CH
3
C(CH
2
CH
3
)
2
CHCH
3
CH
2
CH
3