Today, we show that the free electron model works well for solids because screening is so high that the conduction electrons don't feel the potential from all the other atoms. Shielding is the concept that free electrons will not see the nucleus of an atom because all of the core electrons are in the way.
Welcome to Solid State Physics in a Nutshell. This video series was originally designed to go along with the solid state physics course at the Colorado School of Mines. It follows and references the textbook by Kittel, Introduction to Solid State Physics, 8th edition. As these videos are now being updated to be a worldwide resource, they are also captioned to make viewing possible for everyone, near and far.
It spans 32 video lectures, covering the following topics: 1. Bonding and Crystal Structure 2. Elastic Diffraction 3. Elastic Scattering 4. Phonon Dispersions and Transport & Thermal Properties 5. Inelastic Scattering 6. Free Electron Model: Density of States & Heat Capacity 7. Weak Potential and Band Structures 8. Intrinsic Semiconductors