“Depicting a shape three-dimensional:
For chemists, a process intentional,
As dash-wedge notation,
A visual narration,
Finds clarity through the conventional.”
The 13 April 2023 limerick described dash-wedge notation, a common drawing convention used by chemists to approach the challenge of representing three-dimensional structures in two-dimensional settings (in other words, how they deal with the “depiction restrictions” of the post title).
“Depicting a shape three-dimensional: /
For chemists, a process intentional…”
The three-dimensional structures (shapes) of molecules help explain their functions. A major goal in undergraduate chemistry coursework is learning to read and draw representations of these 3-D shapes from and in two-dimensional settings (e.g., chalkboards and notebook paper).
Some of the drawing conventions are named for the chemists who devised them. The Newman projection and the Haworth projection are named for Melvin Newman and Norman Haworth, respectively. Newman projections allow chemists to consider conformational analysis, and Haworth projections help model concepts related to carbohydrate chemistry.
“As dash-wedge notation,
A visual narration,
Finds clarity through the conventional.”
Several other such conventions, though, are not named for a specific scientist. Indeed, it seems intriguingly hard (at least via the cursory searches that supplement these poems!) to track down a solid reference regarding the scientists who devised the sawhorse projection or the dash-wedge notation.
The latter, named in this poem, is a “visual narration [that] finds clarity through the conventional.” If a bond is written as a “wedge,” it is meant to be read by a chemist as coming towards the viewer, out of the plane of the screen/page/chalkboard. If a bond is written as a “dash,” it is read as going away from the viewer, behind the plane of that surface. This is a common notation that students learn to represent 3-D molecular structure.
This limerick was a fun chance to simply highlight the rationale behind learning this visual and representational skill in chemistry coursework. Overall, the historical saga of molecular representation in chemistry is fascinating and deserves many more words than the 280 assigned to this poem translation!
Chemphasis 