Drawing, visualizing and interpreting 3-D molecular structure (2019 Community Challenge #2)
Submitted by S. Chantal E. Stieber, Cal Poly Pomona- The instuctor walked around the classroom to help students individually as needed for immediate assessment.
- At the end of the class period, students submitted their work to Blackboard for grading.
- Assignments were graded based on accuracy and quality of the drawings.
Students generally were able to determine the molecular formula and generate connectivity drawings of the displayed 3-D structures, but really struggled with 3-D drawing. Although this was developed for a course with second year students who had completed general chemistry, even older students in the course struggled with this component. However, by the end of class, all students greatly improved in their ability to understand, interpret, and convey 3-D structure.
Many students were surprised and many jokes were made about this being a chemistry art class. Although some students didn't particularly enjoy drawing, all understood the value and felt like they had learned something useful. At the end of the semester, many students remarked that the chemical drawing section was the most useful or interesting.
This in-class activity was designed for a Chemical Communications course with second-year students. It is the first part of a two-week segment in which students learn how to use Chemdraw (or similar drawing software) to create digital drawings of molecules.
In this activity, students are given a blank worksheet and 5 models of molecules were placed around the classroom. Students interpreted the 3-D models to determine molecular formulas, connectivity, and generate drawings that convey the 3-D elements. Once students completed the worksheet by hand, they generated the whole worksheet using Chemdraw.
Students will be able to:
1. Write the formula for a molecule based on a 3-D structure.
2. Draw a molecule based on a 3-D structure.
3. Convey 3-D structure of a molecule in a drawing.
4. Translate molecular connectivity to a drawing that conveys 3 dimensions.
5. Create digital drawings of molecules using Chemdraw or similar chemical drawing software.
- Molecular model set for the instructor to prepare structures before class.
- One computer per student with chemical drawing software such as Chemdraw.
Prior to the activity, students were given a brief presentation with an introduction to basic Chemdraw elements using the Chemdraw manual and existing tutorials (see links provided). VSEPR was also reviewed.
For the activity, students were given 3-D models of molecules, and the color key for atom identity was written on the board (eg. blue = oxygen, black = carbon...). The activity was conducted in a class of 24 students, in which each student had access to a computer. The entire class period was 1 hour 50 min, but the activity could be shortened if fewer molecules are included.
Before class, the instructor built models of molecules using a molecular model kit. It is helpful to have multiple copies of each molecule, especially for a larger class, but not critical. The molecules used for the acitvity can be seen in the faculty-only key, and were chosen to have a range of 3-D structures, but other molecules could be chosen. For example, a coordination chemistry or upper division course could have 3-D printed models of crystal structures used as the starting point.
