# Cis-trans isomers internal energy

Whilst reading about stereochemistry, I came to know that the stability and melting point of cis isomers is lower than trans isomers. By searching on net I've found the reason behind that. But one question arises - why is the internal energy of cis isomers bigger than of trans isomers?

• Do you refer to cyclic or acyclic compounds? In acyclic compounds the trans isomer is more stable while in (small) cyclic the cis is more stable. Thus the internal energy of cis is bigger in acyclic while the internal energy of trans is bigger in cyclic. – user17037 Jun 26 '15 at 20:45

In the image you can see the personal boundary of $\ce{-CH_3}$ is the furthest in the trans configuration and that's wh the trans configuration is more stable than the cis configuration.