Week of 3/6


Today we started by reviewing the 5 basic electron geometries and then I lectured on hybridization.  We spent the first half of class working through Molecular Modeling for you to practice figuring out hybridization.   Then we used the modeling kits to build structures that showed pi bonds.

HW: Finish molecular modeling lab except for L and M


Today we started with organic naming practice and learned two new functional groups: aldehydes and ketones.  Then we talked about the difference between polar bonds and polar molecules and identified the factors that determine if a molecule will be polar or non-polar.  The gist is that if a molecule has lone pairs and has polar bonds it will be polar (unless it is one of those linear shapes that has lone pairs, but bonds are arranged in such away that dipole moments cancel out).  If it just has lone pairs but no polar bonds it might be slightly polar or non-polar.  We would look at the properties to say for sure. Today’s notes.

HW: Finish molecular modeling lab practice. Here’s the answers.


Today we started by building benzene and learning about pi bonding networks that result in delocalized electrons which gives the molecule more stability.   This happens in all molecules that have resonance structures.  Next we went over the naming rules for carboxylic acids and learned to identify various functional groups including ethers, etsters, amines and amides.  The second block you worked on the organic modeling lab.

HW: Finish organic modeling lab (answers)


Today we started w/ pg 13 in the packet to practice determining if a molecule is polar.  Here’s my answer key – but I have to make an amendment to the questions about ions.  In general, we would never say an ion is polar or non-polar. An ion has a charge, therefore it cannot be non-polar (no charges) and it cannot be polar (has BOTH a positive and a negative side). However, we can look at the structure and see why it has the overall charge that it does. NH4+ for example, does not have the polar bonds cancel out b/c all the arrows are pointing towards the center. This means all the electrons in the N-H bonds are located more towards the center of the tetrahedron, leaving the outside positve. Hence, NH4+ is a positive ion.  SF5- has all the polar bonds point out.  The planar dipoles cancel out, but the polar bond on top does not so one would expect this ion to have be more negative on the side with the non-planar F atom.  The positive charge that would be on the S is likely blocked by the presence of a lone pair.

HW: contemplate resonance and its relationship to the pi bonding network


First I had you look for patterns in acid strength trends.  2nd half you reviewed by finishing labs and working on practice tests.

HW: study for test