The quantitative changes in propagation, antenna impedance, radar cross section, breakdown, and emissivity characteristics resulting from hypersonic plasmas depend on the electrons and heavier particles present. To determine these number densities for normal and oblique shocks, aerothermodynamic theory is applied to relate macroscopic properties on both sides of the shock front by means of the flow conservation equations. Composition and energy of the shocked air at assumed velocities, densities, and temperatures are then obtained using the law of mass action and the principles of statistical quantum mechanics until the conservation equations are satisfied.