Blog Entry 11/3/13

This week in AP Chemistry, we started off by pondering the effects of the charge and size of an ion on melting and boiling points. We were given a question on the projector screen along with a few choices. Without any discussion with our tablemates, we voted on the choice we found most correct. It was quite similar to the Socrative website we used earlier in the tri. After voting individually, we discussed the question with our tablemates and came up with an answer we all agreed on. Many times, there was a wide variety of answer preference. Other times, however, there was dispute between two choices. I particularly remember having a very engaging discussion about one of the questions, and our table ended up being split in half on what answer we thought was correct. After our table discussion, we saw the correct answer and discussed why the other choices would not have been correct. Coulomb’s law was especially important when thinking of the solution.

The ConcepTest was quite helpful for me, and I hope we do more in the future. The discussions I had with my tablemates really helped me view different ways of approaching a problem, and based on their logic, I often changed my answer when I felt their explanation was more reasonable.

On Tuesday, we started a new POGIL on intermolecular forces. My experience in Latin class already gave me some prerequisite knowledge on the subject, the Latin word “inter” means between, so I assumed that intermolecular forces were forces between molecules. “Intra” means within, and those are the forces within a molecule. We had dealt mostly with intramolecular forces before this week during our covalent bonding unit.

In the middle of the week, we explored why ice is slippery. We all know that it’s difficult to walk on an icy surface without our feet slipping out from underneath us, but we were baffled when asked why this is so. We explored the question at the molecular level by using models of water molecules and simulating the structures of ice and water. When we created the molecular structure of ice, which is a ring-like structure filled with many gaps, it took up a lot of space. This explains why when water is frozen, it expands in the container it is in.

We used our hands to represent the pressure of an ice skater’s blade on the surface of ice. When we pushed down on the ice structure with our hands, the structure collapsed and assumed the structure of water again. Basically, when a skater’s blade makes contact with the ice, the molecules directly under the blade turn into water and cause the ice to be slippery.

Due to catching the nasty cold that has been going around the school, I was unable to attend class on Thursday and Friday. However, I heard we whiteboarded much of the intermolecular forces POGIL and I also stayed caught up by watching the lectures and completing the lecture quizzes. We discussed liquids and solids, and also further discussed intermolecular forces, the strongest of which is hydrogen bonding.