UTC: Thursday, February 21st, 2019

Here’s the annual, November bonding rant!

Maybe I teach this topic really, really badly. I think what’s closer to the truth, is that it takes time for kids to get a good handle on the semantics and language of bonding terminology. Teaching AP Chemistry to sophomores that have no chemistry background, in one year, doesn’t afford us that luxury. I’ve written […]

No biologists, breaking bonds does NOT ‘release energy’

An age old problem that I’ve become a little weary of addressing, so let’s clear this up really quickly and really simply. No biologists, breaking bonds does NOT ‘release energy’, and here’s why. Bond breaking is an endothermic process (+ve), and bond making is an exothermic process (-ve). All chemical reactions involve both processes, and […]

Bonding answers AGAIN! Grrr…

I’ve just finished grading a test on bonding done by my AP students, and as usual, there are several issues relating to the phraseology and wording of their answers that need to be corrected. I’ve addressed these problems previously here (and you should read that post first), and I’ve also written similar posts in relation […]

Choosing between resonance and hybridization

A question came up on the College Board’s AP chemistry discussion group recently that I have seen many times before (including many variations of the same), and that often confuses students. It usually looks something like this; The fact that the nitrogen-to-oxygen bond lengths in the nitrite ion are all the same, can be attributed […]

Writing good answers to AP Bonding problems

Updated 11/16/13 After the positive reaction to this post, @mcford19 suggested that I write another, similar one about writing good answers to AP Bonding questions. Here it is. Again, here I am not really trying to address the chemistry per se, rather I’m trying to address the way kids write their answers. The language, phraseology, […]

Formal charge & Lewis structures

Following this post at the end of last month, I wanted to add some more notes about formal charge and Lewis structures, and their use on the AP exam. This question seems to come up a lot on the AP listerv and in my email inbox. Formal charge is certainly overused as a diagnostic tool by […]