Difference Between Between Cis and Trans Isomers

When we are studying about isomers in chemistry, we will come across various types of isomers. While they are mainly divided into two groups namely constitutional isomers and stereoisomers there are more sub-type of isomers that we need to learn about. As such, cis and trans isomers are such type of isomers which we will learn about here in this page. We ‘re going to research what these isomers are and the main distinctions between cis and trans.

Usually, cis and trans isomerism can be found in organic and inorganic compounds, alkanes and in alkenes. Cis isomers are isomers in which two similar atoms lie on the same side of a double bond in the molecule. On the other hand, trans isomers feature molecules with two similar atoms placed on opposite sides of a double bond. Cis and trans isomers have the same molecular formula and molecular weight, but they are known to differ in some aspects.

Difference Between Cis and Trans Isomers

When we talk about the difference between cis and trans isomers, one of the main differences is in the arrangement of the atoms in a double bond. However, we will look at some other key differences between the two below.

Difference Between Cis and Trans Isomers
Cis Trans
Cis isomers are molecules with the same connectivity of atoms. They feature similar side groups placed on the same side of a double bond. Trans isomers feature molecules with similar side groups placed on opposite sides of a double bond.
Cis isomers are almost always polar. Trans isomers are not very polar. Many trans isomers are non-polar molecules.
Due to loosely packed molecules, cis isomers have relatively lower melting points than trans isomers. Due to tightly packed molecules, the melting points of trans isomers are usually higher than those of cis isomers.
Likewise, due to the presence of strong attractive forces between atoms cis isomers have a high boiling point. The boiling point is comparatively low for trans isomer as there are no strong attractive forces.
Cis isomers in inert solvents have a strongly soluble content. A solubility in neutral solvents is smaller.
Both forms of isomers have higher acid power. The protons aren’t readily emitted in trans isomers. So it has less acidic strength.

These are some differences between cis and trans isomers. To know more about isomers and other chemistry topics you can keep visiting BYJU’s or download our app for interesting content and learning experience.

Related Links:

Test your knowledge on difference between cis and trans!


  1. Which of the cis and trans isomers is at the higher energy state?

    1. Trans isomer is always stable and exist at lower energy state. On the other hand cis isomer is at higher energy state and unstable.

Leave a Comment

Your Mobile number and Email id will not be published. Required fields are marked *