This is an interactive Wolfram demonstration showing basic Lewis structures for 2 - 6 electron domains.
Type of Material:
Could be used for lecture to show the different shapes or as a homework allowing the student to "experiment" on their own with the shapes.
Wolfram CDF Player or Mathematica needed. Available for download from this website.
Identify Major Learning Goals:
The objective is to get the students to realize how the combination of electron domain and molecular geometries generate the overall molecular shape in accord with the Lewis structure formalism.
Target Student Population:
High school AP chemistry students and University 1st year students that are taking general chemistry and starting VSEPR theory.
Prerequisite Knowledge or Skills:
The user will need to know Lewis dot structures and a basic understanding of VSEPR to be able to use this program.
The app is convenient to load, quick to load and it is easy to manipulate the structures with mouse over.
The structures are small, the central atom has the same color as the peripheral atoms (which is terribly misleading) and the unshared pairs of electrons are not represented.
Potential Effectiveness as a Teaching Tool
There is a very limited ability for this app to increase the students mastery of the 3-dimensionality implied by Lewis structures.
All the atoms are the same - why not add a button that can change the color and size of the atoms so the student can see what happens to the bond length and the angle when bigger atoms are used. There is no change in the angle when lone pairs are present and that could confuse students. Why not add a note that when lone pairs are present angles are slightly smaller? Better yet, use real compounds as demos.
Ease of Use for Both Students and Faculty
The interface is relatively intuitive.
There are no instructions that I could find. All molecules are imaginary but it would be a nice addition to see real compounds to illustrate each molecular shape and electron domain.
Other Issues and Comments:
Consider the use of space filling models. Color atoms according to type. Include electron domains. Use real molecules as examples, in addition to the stylized generic molecules.
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