Topics: VSEPR theory, Chemical bond, Molecule Pages: 2 (488 words) Published: August 18, 2012
In this assignment, you will build models of molecules in order to answer questions about their shape and chemical properties. Materials:
* multicolored gumdrops, marshmallows, or other soft candy (to represent atoms in each model) * toothpicks (to represent the covalent bonds in each model) * paper (to draw Lewis dot structures and pictures of the models) Introduction:

Chemists often use three-dimensional models to help represent the geometry, or shape, of molecules. You can purchase a molecular modeling kit at university stores or on the Internet, but in this activity you can make your own kit using the items listed above. You can select any candy that you prefer, as long as the candies can stick on the end of a toothpick without falling apart and there are at least three colors to represent different elements in a molecule. Procedure:

1. Draw the Lewis structure for each of the molecules listed below. CCl2F2, HCN, H2O, NH3, H2S, SO2, PCl4+, NO3-, O3
1. Build a model of each of the Lewis structures using candy and toothpicks. In each molecule, represent each element with a different colored candy. Each toothpick represents two electrons. A toothpick between two atoms represents a single bond, two toothpicks between two atoms represent a double bond, and three toothpicks between two atoms represent a triple bond. Remember that the lone pairs on the central atom take up space and play a role in determining the shape of the molecule. Represent each lone pair (nonbonded pairs of valence electrons) on the central atom with a nonbonded toothpick. The bonds and lone pairs on the central atom should be spread apart as much as possible. 2. Refer to the VSEPR theory to check the shape of each of the molecular models that you built. Conclusion:

(Copy the following questions into your assessment document. You may copy and paste the table, or create a similar table in the document.) 1. After completing the molecular models, fill in the table below:...
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