Molecular Geometry
You will want to familiarize yourself with chapter 10, "The Shapes of Molecules", in your text, Chemistry: The Molecular Nature of Matter and Change, 3rd edition by Martin Silberberg, before beginning this lab. By following the link, you can read through a summary of chapter 10 (it may take a minute for all the graphics to download) that gives the steps for drawing molecules and predicting their shapes.
About the Assignment
To complete this lab assignment, you will be accessing a website that requires the CHIME plug-in. The plug-in is available on the school computers; however, you will probably need to install it on your home computer. If you can see the structure below, the plug-in has been correctly installed.
Getting the Plug-In:
Using an ITAP computer on campus
Using the Plug-In:
NOTICE by looking at the 3D model simulations, you can see the name for the molecular geometry comes from the shape of the compound when the lone pairs on the central atom are ignored.
For Example:
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|
|
|
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BF3 |
NO2 |
|
# of lone pairs |
0 |
1 |
|
# of bonding pairs |
3 |
2 |
|
VSEPR number |
3 |
3 |
|
electronic arrangement |
trigonal planar |
trigonal planar |
|
molecular geometry |
trigonal planar |
bent |
You should familiarize yourself with the different shapes (and the corresponding names) that result from replacing outer atoms with lone pairs.
Practice Problems:
Check your understanding with a few practice problems. The practice problems are intended for you to test yourself and see if you understand how to draw Lewis Dot Structures and predict molecular geometries. These problems are for you alone and will not be graded.
Molecular Geometry Lab:
All parts of the assignment (Molecular Geometry Lab - Parts I, II(a), II(b) and III) are to be answered in your lab notebook. You should follow a specific format for entering your answers in your notebook.
You can access any part of the lab assignment with the following links.
