band Gap: Solid state physics, Solid, Electron, Electronic structure, electron volt, Valence band, Conduction Insulator (electrical), ... shell, Atomic nucleus,

Conduction Band: Solid state physics, Semiconductor, Electrical insulation, Electron, Valence band, Atom,...

Valence Band: Solid, Electron, Energy, Absolute Zero, Atom, Conduction Electrical Conductor

Free electron model: Solid state physics, Valence electron, Crystal structure, Metal, Solid,...