What is a Skeletal Structure?

Folinic acid
Skeletal formula (chemical structure) of folinic acid (leucovorin) drug molecule. Used as adjuvant during cancer chemotherapy.

ALFRED PASIEKA/Getty Images

by Anne Marie Helmenstine, Ph.D.
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
Updated August 26, 2018

A skeletal structure is a graphical representation of the arrangement of atoms and bonds in a molecule.

2-D and 3-D Arrangements

Skeletal structures are shown in two dimensions where element symbols are used for the atoms and solid lines to represent bonds between them. Multiple bonds are represented by multiple solid lines. ​Double bonds are shown with two lines and ​triple bonds are shown with three lines.

Carbon atoms are implied when two bonds meet and no atom is listed. Hydrogen atoms are implied when the number of bonds is less than four on a carbon atom. Hydrogen atoms are shown if they are not bonded to a carbon atom.

3-D arrangements are represented by solid and hashed wedges. Solid wedges imply bonds coming towards the viewer and hashed wedges are bonds pointing away from the viewer.