What distinguishes cis isomers from trans isomers in molecular structure?

Cis isomers are characterized by having substituents on the same side of a double bond, while trans isomers have substituents positioned on opposite sides. This arrangement significantly affects the physical and chemical properties of the molecules, including their polarity, boiling points, and steric interactions.

In a cis configuration, the presence of substituents on the same side can lead to increased steric strain and make the molecule more polar due to the asymmetrical shape it creates. In contrast, the trans configuration is generally more stable because the substituents are farther apart, thereby reducing steric clashes and potential strain. This distinction is crucial in organic chemistry and biochemistry as it influences how molecules interact with one another, impacts their reactivity, and determines their biological functions.

Understanding these differences is fundamental in fields such as medicinal chemistry and molecular biology, where the spatial arrangement of atoms can significantly alter the behavior of compounds in biological systems.