Before the advent of quantum mechanics, solid state physics was a collection of empirical observations. Drude’s model of electron conductivity worked occasionally but failed spectacularly for heat capacity. The mystery of why electrons didn’t spiral into the nucleus inside a metal remained unsolved.
Kittel excels at providing a physical "feel" for the material before diving into complex equations. quantum theory of solids kittel pdf best
Before you commit to hunting down the PDF, ask yourself: Do you actually need this book, or do you need a bridge? Before the advent of quantum mechanics, solid state