The nature of light....

Friday in class exams were returned. The average was up a bit (around 120/150) on the exam, and now that we have 3 exams in the books we can start making a little more informed projection of course grades. Given the current scores and distribution, if I drop everyone's lowest exam score it looks like the syllabus grade cutoffs are appropriate: 90.0% for A's, 80.0% for B's, 70.0% for C's, 60.0% for D's. I typically use +/- grades, so if you're are the very top or bottom of one of those ranges you will likely see a + or -. We still have 1 regular 150pt exam and a 200pt final exam and a few more Mastering Chemistry assignments, so there are quite a few points still out there to be earned (or lost). As a point of reference, the class is worth 750pts total. Add up your 2 highest exam scores and your current percentage in Mastering Chemistry to see how many more points you have to earn to reach your goal grade. An A will probably require >675pts, B>600pts, C>525pts, D>450pts.

We also started talking about the nature of light as described in Chapter 7. I didn't go over every little detail, your textbook does a fine job of that. We'll put that discussion of light into an atomic context Monday in class.

Have a good weekend and don't forget to set your clocks back on Saturday night/Sunday morning.