In general chemistry, isomers are two or more elements that have the same number of protons but differ in mass number. In organic chemistry, the compounds are cis or trans isomers if they have the same chemical formula, but differ in the placement of functional groups based on molecular geometry. Cis isomer is when two like functional groups are on the same side of the molecules, while trans isomer is when the like functional groups are on opposite sides.
The cis-trans isomers are shown in the picture. As you can see, in the cis isomer, the methane functional group are both in the same side. Same as well with the hydrogen atoms. On the other hand, these functional groups are opposite to each other in the trans isomer.
The cis-trans isomers are shown in the picture. As you can see, in the cis isomer, the methane functional group are both in the same side. Same as well with the hydrogen atoms. On the other hand, these functional groups are opposite to each other in the trans isomer.