The Lorentz model consists of non-interacting, point particles moving among a collection of fixed scatterers of radius a, placed at random, with or without overlapping, at density n 6 in space. This model was designed to be, and serves as, a model for the motion of electrons in solids. The kinetic equation for the moving particles must be linear, and for low scatterers density, nad >> 1, it is the Lorentz-Boltzmann equation. If external fields are absent, the Chapman-Enskog method leads to the diffusion equation. For three dimensional systems with hard sphere scatterers, the Lorentz-Boltzmann equation can be solved exactly, and the range of validity of the Chapman-Enskog solution can be examined. Electrical conduction and magneto-transport can be studied for charged, moving particles. In both cases there are unexpected results. The Lorentz model with hard sphere scatterers is a chaotic system, and one can calculate Lyapunov exponents and related dynamical quantities.