Question

What are the E and Z isomers of 3-methyl-2-pentene?

Answer 1

This can be written as `CH_3-CH=C(CH_3)-CH_2-CH_3`

Explanation:

Now there are two possible isomers, because the `=` is inflexible:

The Z-isomer where the stuff left of the `=` is at the same side of the `C=C` as the stuff on the right, so both down or both up (from German Zusammen=together).
The E-isomer where they are on opposite sides (from Entgegen=opposite).

Note: They are also called cis- (Z) and trans- (E).