Reading: Chapter 10, Modern Physics, Harris.

I would somewhat recommend reading Chapter 10 of Harris, Modern Physics, which cover things like: molecules, crystalline solids, conductors (metals), semiconductors and semiconductor device physics. Skip the section on vibration and rotation. Although we have not been really following the book so far, I think this chapter may be helpful in understanding this material, which encompasses a lot of phenomenology.

Note added Feb. 23. I believe that the book includes 2 approaches to the formation of energy bands in crystals and this can be confusing. One is that each band comes from an atomic energy level and state, the other is the free-electron approach. While both have their uses, the first approach, in which each band arise from a particular atomic state is the better one in my view. I would take anything you read (anywhere) about the free-electron approach to band theory with a grain of salt.
Please post any questions or comments related to the reading here. If something there seems different from what I have said, please bring that up here. If anything seems unclear in general, it is helpful to everyone to bring that up for discussion here.
Over the next week or two we will be covering things like electrons in crystals, semiconductors, semiconductor lasers, leds and solar cells and related topics.