Cis-2-butene is a geometric isomer of butene where the carbons are on the same side of the double bond. Cis and trans isomers have the same molecular formula but different physical properties due to restricted motion from the double bond and differing dipole moments. Cis-2-butene specifically has all carbons on one side of the double bond, as opposed to across from each other in trans isomers.

1. Geometric Isomers cis 2butene

2. Definition
• Cis and trans isomers are the same because they have the same
molecular formula but have different physical properties.
• Cis and trans isomers both have restricted motion because of the
double bond.
• The cis- prefix means “on this side” because the carbons are formed
on the same side. Then trans- prefix means “across” because they are
on opposite sides.

3. Picture
Cis 2-butene.
The carbons are all on one side.

4. Picture
• Picture 1. The difference between cis and trans butene.
• Picture 2. Another picture of cis 2-butene

5. Additional fact
Cis and trans isomers also differ because of the overall dipole moment.
http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Cis-trans_isomerism.html

6. Summary
• I learned that cis means “on this side” and trans means “across.”
• Also, cis 2-butene and trans 2-butane have different physical
properties.