Wedge and Dash Projection Definition and Example

What Wedge-and-Dash Means in Chemistry

This is the wedge and dash projection of methane.
This is the wedge and dash projection of methane.. Todd Helmenstine

Wedge and Dash Definition

A wedge and dash projection (wedge-and-dash) is a means of representing a molecule (drawing) in which three types of lines are used in order to represent the three-dimensional structure: (1) solid lines to represent bonds which are in the plane of the paper, (2) dashed lines to represent bonds that extend away from the viewer, and (3) wedge-shaped lines to represent bonds oriented facing the viewer.

Although there is no hard-and-fast rule for drawing a wedge and dash structure, most people find it easiest to visual the three-dimensional shape of a molecule if the pair of bonds in the same plane as the paper are drawn next to each other, with the bonds in front of and behind the plane drawn next to each other (as in the example shown).

Although the wedge-and-dash is the most common method of representing molecules in 3D, there are other diagrams you may encounter, including the sawhorse diagram and Newman projections.