# What are the differences between geometric isomers and optical isomers?

Feb 5, 2017

Well..........

#### Explanation:

And see here for here a discussion on diastereoisomerism.

Just to review the levels of isomers, structural isomers are species with the same chemical formula but different connectivity. Geometric isomers have the SAME connectivity but different geometry. The best illustration of geometric isomerism occurs with cis and trans $\text{2-butylene}$. For both cis and trans isomers the CONNECTIVITY is definitely the same: i.e. $C 1$ connects to $C 2$.....connects to $C 4$. However, because of the geometry around the olefinic bond between $C 2$ and $C 3$, these isomers are distinct chemical species, with different chemical and physical properties.

Chirality, handedness, adds another level to isomerism. Enantiomers have EXACTLY the same connectivity, and geometry, however, one enantiomer is the mirror image of the other. Introduce a couple of so-called chiral centres into the molecule, and diastereomers can be generated, i.e. $\text{RS}$, and $\text{RR}$, which are diastereomeric in the respect that they are not MIRROR images.

If there is something I have ignored fire away.