Summer Research Program for Science Teachers

Compton Mahase

Fieldston School, Bronx, NY



Investigating the Shapes of  Covalent Molecules and Measuring their Respective Bond Lengths and Bond Angles Using Chem 3D, a Computer Modeling Program


Objectives:     1.  Draw Lewis structures for common covalent molecules.

2.     Make predictions about molecular shapes.

3.     Draw covalent molecules using Chem 3D computer program.

4.     Collect an organize data.

5.     Make conclusions from data.


Activity:         1.  Students will draw Lewis structures of common covalent compounds.  Appropriate examples include methane, ammonia, water, carbon dioxide, ethane, ethene, ethyne, phosphorus pentachloride and sulfur hexafluoride. [9-12 Content Standard B- Structure of atoms/matter]

                       2.     They will be asked to predict the shapes of the molecules using VSEPR theory. [Content Standard Unifying Concepts- Models and explanation]

3.     They will then use Chem 3D  Pro(a computer modeling program) to draw the molecules and measure the bond lengths and angles of the molecules.  They will also examine the 3D shape of the molecules and name them using information from their text and other available literature.  Numerical information will be tabulated in data tables. [9-12 Content Standard E- Understandings about science and technology]

4.     Students will then be asked to formulate rules that others can use to predict shapes of molecules,  as well as, bond lengths and bond angles. [9-12 Content Standard A- Formulate explanations using evidence]



Extensions:  This activity can be extended to common polyatomic ions.

Evaluation: Students will be asked to predict the shapes, bond lengths and bond angles of unfamiliar molecules using the rules they formulated.



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