Grading chiral molecules
The Lewis Structure Drawing Tool can correctly grade chiral molecules. Chiral atoms are indicated using hashed (
or 
) and solid (
) wedge bonds.
Note: Chiral grading does NOT support Fischer projections or Haworth structures.
Answers can contain molecules with single or multiple chiral centers. Molecules with multiple chiral centers include:
- Chains and rings where chiral atoms are adjacent or nonadjacent
- Molecules with more than two chiral centers
Hashed-wedge vs. Solid-wedge Bonds
Students can draw correct hashed-wedge bonds may with the skinny or the fat end of the wedge towards the chiral carbon ( or ) as long as the direction chosen is consistent within the same molecule. The tool also enables drawing the bonds in either direction, for incorrect answers.
Acceptable correct answers:
Incorrect answers for which you can write wrong answer responses (WARs):
To correctly draw solid-wedge bonds, the skinny end of the wedge ( ) must be toward the chiral carbon. When writing WARs, you can code in either direction.
Correct answers require solid-wedge bonds for atoms going out of the plane of the page, and hashed-wedge bonds for atoms going into the plane. Don’t draw structures similar to those shown below, even for wrong answers.
Incorrect answers you should never use:
Chiral Centers
If there is one chiral center, wedge bonds can be on both sides of the chiral carbon.
Acceptable correct answers:
Chiral centers must be connected with a line bond. NEVER draw structures with wedge bonds connecting chiral centers, even for wrong answers.
| Acceptable correct answer: | Incorrect answer:
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If a hydrogen atom is attached to a chiral center, as shown below, hydrogen atoms must be graded.
See also: