Category Archives: CHM 111 Class Notes (Spring 2009)

CHM 111: Board notes from 1/21/09

Here are the notes from Wednesday’s CHM 111 class. These notes continue our discussion of valence bond theory from Chapter 10, then introduce the phases of matter from Chapter 11.

[CHM 111: 1/21/09 notes]

We discusses several chlorine-containing hydrocarbons during our talk about how double bonds work in valence bond theory.  Here they are.

This is 1,2 dichloroethane. Both ends of this molecule are free to rotate around the C-C bond.

This is 1,2 dichloroethane. Both ends of this molecule are free to rotate around the C-C bond.

This is cis 1,2-dichloroethene. Both of the chlorine atoms are on the same side of the C=C bond. The chlorine atoms are fixed in this position because the double bond does not allow free rotation, since rotation would break the pi component of the double bond.

This is cis 1,2-dichloroethene. Both of the chlorine atoms are on the same side of the C=C bond. The chlorine atoms are fixed in this position because the double bond does not allow free rotation, since rotation would break the pi component of the double bond. This illustration shows electrostatic potential, and we can see that this molecule is polar.

This is trans 1,2-dichloroethene. The chlorine atoms are on opposite sides of the C=C bond. The chlorine atoms are fixed in this position because the double bond does not allow free rotation, since rotation would break the pi component of the double bond. This illustration shows electrostatic potential, and we can see that this molecule is nonpolar. It also has observably different physical properties (like boiling point) from the cis form.

This is trans 1,2-dichloroethene. The chlorine atoms are on opposite sides of the C=C bond. The chlorine atoms are fixed in this position because the double bond does not allow free rotation, since rotation would break the pi component of the double bond. This illustration shows electrostatic potential, and we can see that this molecule is nonpolar. It also has observably different physical properties (like boiling point) from the cis form.

CHM 111: Board notes for 1/14/09

Here are the notes from today’s CHM 111 class.  These notes discuss polarity and molecular shape, and introduce valence bond theory.

[CHM 111: 1/14/09 notes]

Here area few 3D renderings of some of the molecules we discussed in class.  You can click each image for a larger version.

You can see that each of propane's three carbon atoms have a tetrahedral geometry.

You can see that each of propane's three carbon atoms have a tetrahedral geometry.

Ethanol's two carbons are both tetrahedral, while the geometry around the oxygen atom is bent (a derivative of tetrahedral).

Ethanol's two carbons are both tetrahedral, while the geometry around the oxygen atom is bent (a derivative of tetrahedral).

This molecule is polar, since fluorine is able to draw electrons towards itself.

This molecule is polar, since fluorine is able to draw electrons towards itself. This picture is shaded to show electrostatic potential: blue for negative, and red for positive.

Even thought it's not immediately obvious from the Lewis structure (see the notes for the structure), this molecule is polar. In three dimensions, you can clearly see that the fluorine atoms are on the same side of the molecule.

Even thought it's not immediately obvious from the Lewis structure (see the notes for the structure), this molecule is polar. In three dimensions, you can clearly see that the fluorine atoms are on the same side of the molecule.

CHM 111: Board notes for 1/12/09

Here are the notes from today’s CHM 111 class. These notes discuss VSEPR and molecular shape for simple molecules.

[CHM 111: 1/12/09 notes]

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