10.21.13 - WebMO, hybridization, sigma/pi bonds, test next week

WebMO

This week, we've mostly worked out building our VSEPR balloon models on WebMO. To build a model on WebMO, we first placed out elements on the program and submitted it to clean up the shape of the structure. Then, by creating the structure, we were able to determine the angle measures, the dipole moment, the charges of the elements, and we were able to build the space filling models.

Here are some examples:

By building these models, we were able to understand the dipole moments, polarity, electron domain geometry and the molecular domain geometry. This activity really helped me with determining the different domain geometries and the angles that correspond to each molecule.

Hybridization

I believe we were introduced hybrid orbitals in one of the lecture quizzes, however this week we went over some examples for homework. sp corresponds with two hybrid orbitals, with angle measures of 180 (linear). sp2 corresponds with three hybrid orbitals with angle measures of 120 (trigonal planar). sp3 has four hybrid orbitals with angle measures of 109.45 (tetrahedral). Although there use to be a theory that the d orbitals also exist, we no longer learn this in class because there is doubt in the theory. So, anything above four hybrid orbitals does not have a hybrid orbital.

sigma/pi bonds

On Friday, we went over a little about sigma and pi bonds to clear up some confusion we had since out lecture quiz. A single bond is always a sigma bond. When there is a double bond, there is a sigma and pi bond.

Here is a picture of a diagram of CO

In this way, there are one sigma bond and two pi bonds that make the CO molecule covalent.

Test Next Week

We have a test next week on Tuesday. We will be tested on drawing Lewis structures, calculating formal charges, resonance structures, bond length and strength, VSEPR models, bond order, bond angles and their reasons, shapes of the Electron Domain Geometry and Molecular Domain Geometry, hybridization, polarity, and other material we have covered in this unit.

Main Ideas

This week, the main idea was to become comfortable with the uncertainties we had since our lecture quizzes. Practicing the electron domain geometry and the molecular domain geometry on the WebMO really helped me because I got more practice and understanding to why the molecules take the shapes they take. I'm still unsure about fully understanding the material for this unit. For example, what is the difference between a sigma bond and a pi bond? I understand that there are two different types of bonds in a double bond or triple bond, but I don't know what the differences are. I would like to relearn the unit with a deeper understanding if I ever have time before the AP exam. I still need to work on understanding the general ideas of all the topics (under Test Next Week) because I mix up a lot of the concepts we've learned over the past few weeks, like hybridization and polarity. However, my ideas have changed about atoms: I know they are much more complicated than what I assumed they were like!