From Atomic Orbitals to Energy Bands: An Introduction to the Electronic Structure of Solids and Electrical Conductivity

A step-by-step introduction to the electronic structure of solids and electrical conductivity, written for first-year physics students. The paper develops one continuous line of reasoning: discrete orbitals from the Schrödinger equation, bonding and antibonding molecular orbitals, energy bands in a crystal, the Fermi level, and finally electrical conductivity. All calculations are carried out explicitly, and the historical primary sources are cited throughout. The repository contains the LaTeX sources, the scripts that generate every figure, and the compiled PDF.