Week 6

This week in AP Chemistry we examined the hybridization theory held by many modern scientists. We were reminded early on that it was very important that we remember that this particular conjecture is a theory and there is currently an ongoing debate over many of the specifics of these processes, with data to support all sides of the debate. In class, we took extra care to focus on the areas with less debate, that scientists are much more sure of. In the case of hybridization, scientists are most sure of the hybridization of molecules with two to four electron domains around the central atom. The hybridization for the molecules is sp,sp2 and sp3 (numbers should be superscript), for molecules with two, three and four electron domains, respectively. These names mean that the hybridized orbitals were formed from the combination of an s-orbital and that particular amount of p-orbitals. For molecules with five or six electron domains, it had been believed, until a few years ago, that d-orbitals were involved with these hybridization, but today it is more widely accepted that molecules with these geometries do not hybridize at all.

Many students initially struggled with the idea of hybridization. For me in particular, it seems that this was mainly a result of not being able to see the significance of hybridization, and how the orbitals combined to make these many different shapes, struggling to draw the connection from the various-shaped orbitals we learned about over the summer and the uniformity of the ones presented to us now. The biggest help came when it was simply broken down into the relationships between hybridization, electron domain geometry and the number of electron domains. Simply, if you know any of this information, there is only one possibility for each of the others for that molecule. To check or solve, all you need to do is add the superscripts to get the number of electron domains to find the electron domain geometry, in any order.

Along with the introduction of hybridization, this week we analyzed some relatively ordinary molecules in a very advanced way with the use of the WebMO program and a supercomputer from Hope College. This program allowed us to find many important details about each molecule with incredible accuracy simply through entering the structure of the molecule (atoms involved and bonds). These details include all bond angles, dipole moments, individual partial charges on each atom, and manipulable space filling diagrams to show polarity (pictured below). In class we all filled out a chart with this information after building certain molecules, on for each electron and molecular domain configuration. I noticed that all bond angles followed our rules for these geometries, the standard angles for those without unshared pairs and less than the standard angles for those with unshared pairs repelling the bonded pairs.

For an overview of electron and molecular domain geometries with example molecules go to the link below:
http://www.sparknotes.com/testprep/books/sat2/chemistry/chapter4section8.rhtml

NSF (Thiazyl Fluoride) space filling diagram from WebMO