Drawing Molecules: Organic Chemistry

The molecule drawing module provides a canvas and tools for drawing molecules in Sapling Learning. Different atoms, bond types, stereochemistry, charges, lone electrons, and reactions can be drawn using this module. Grading is based on the atoms and connections between them, not on the orientation of the molecules, making the drawing experience as much like paper homework as possible.

Note: The drawing module is not "picky!" We don't grade bond angles or bond lengths, for example.  If, after viewing the solution to a question (or eventually getting it correct), you think you were scored incorrectly, please let us know at support@saplinglearning.com. Be sure to include the assignment name and question number, and details about what you think was scored incorrectly.

Some tools are specific to the organic chemistry mode and will not appear if they are not available for a particular activity.

The animation below provides an introduction to drawing molecules for organic chemistry (scroll down for more tips):

Drawing Tips

For drawing questions, there are some things to be aware of to ensure that your answers are graded properly.

Always Draw Connections

The molecule drawing module grades connections, not the visual representation of the molecule. That means you can draw your molecules in any orientation, but you must indicate all connections; you can't simply draw two overlapping lines and expect the system to know you meant for there to be a carbon atom in the middle.

To help remind you how this works, "hidden" carbon atoms are indicated with light gray dots in graded molecules. If you don't see a gray dot, the system doesn't see a carbon atom.

Hydrogen Atoms

Normally, hydrogen atoms attached to carbon atoms do not have to be shown. You may add them if you like (just be sure to add the correct number). The grading options within the drawing module will tell you if hydrogen atoms must be included on carbon atoms.

Hydrogen atoms must always be included on any non-carbon atom. A common source of mistakes is forgetting to add the hydrogen atom(s) (and/or charge) on atoms such as oxygen and nitrogen.

There are two ways to add hydrogen atoms to a non-carbon atom (X):

1. Draw the X-H bond, as shown with the O-H group below, or
2. Use the "add hydrogen atoms" button to change an X atom into an XH_n group, as shown with the NH₂ group below. (Note: the button may be disabled in some questions).

Perspective Drawings

When drawing stereoisomer structures with wedge-and-dash bonds, the skinny end of the wedge bond must point towards the chirality center (asymmetric atom). Note: Our style is to always point the skinny end of dash bonds toward the chirality center. This style may differ from what you have seen in your textbook.

Also, if a chirality center contains a hydrogen atom, then the hydrogen must be drawn to ensure proper grading. In addition, the order of wedge, dash, and normal bonds around the chirality center can matter for grading.

See Drawing Molecules: Chirality for a video demonstrating this process.