Modeling Exercise # 2 -- continued

Total time: 3 minutes

Task 4A: Measure the bond angle in water

1. Begin with the water molecule you built and optimized in the previous tasks. Select File|Open "water-MM3"
2. Click on the select tool,, select one hydrogen, then hold down the shift key and select the oxygen and another hydrogen.  All three atoms (and the bonds) will be highlighted.
3. Select Adjust|Bond Angle. The Set Bond Angle dialog box opens displaying the bond angle in degrees. There are several things you can do: label, record or adjust the angle.
4. Record the value on the work sheet.
5. Now, let's label the bond angle in water.
 
6. Select Define Geometry Label, then Unlock Geometry and click OK. A label appears on the bond angle in the workspace window.
7. Click on the select tool,, and click anywhere in the work space to select the entire molecule.

Task 4B: Measure the bond length in water

1. We'll continue with the same molecule.
2. Click on the select tool,, select the oxygen, then hold down the shift key and select one of the hydrogen atoms.  The oxygen and one of the hydrogen atoms will be highlighted.
3. Select Adjust|Atom Distance. The Set Atom Distance dialog box opens displaying the bond length in angstroms. There are several things you can do: label, record or adjust the bond length.
4. Record the value on the work sheet.
5. Now, as in the last exercise, let's label the bond distance in water.
 
6. Select Define Geometry Label, then Unlock Geometry and click OK. A label appears on the bond length in the workspace window.

This is the last task in this exercise.  Go back to the start page.