The Meaning of Wavy Lines in Skeletal Structures

Skeletal Structures and Stereoisomerism

Blue molecules
Skeletal structures describe three-dimensional molecules without being 3D.

cdascher, Getty Images

 Wavy lines in skeletal structures are used to show information about stereoisomerism. Typically, wedges are used to denote a bond bending out from the plane of the rest of the molecule. Solid wedges show bonds bending towards the viewer and hashed wedges show bonds bending away from the viewer.

Wavy Lines in Skeletal Structures

Valine Stereostructures
These skeletal structures show the different stereoisomer representations of the amino acid valine. Todd Helmenstine

A wavy line can mean two things. First, it can denote the stereochemistry is unknown in a sample. The structure could be marked either solid or hash wedged. Secondly, the wavy line can denote a sample containing a mixture of the two possibilities.

The structures in the image pertain to the amino acid valine. Amino acids all (except glycine) have a chiral center carbon adjacent to the carboxyl functional group (-COOH). The amine group (NH2) bends out from the plane of the rest of the molecule at this carbon. The first structure is the general skeletal structure with no concern for stereochemistry. The second structure is the L-valine structure found in the human body. The third structure is D-valine and has the amine group bending opposite of L-valine. The last structure shows a wavy line at the amine group showing either a sample containing a mixture of L- and D-valine or it is valine, but unknown if the sample is L- or D-valine.

More About Amino Acid Chirality​

 Learn more about chirality and how it relates to amino acids: