The Kohn-Sham orbitals build the exact electron density, i.e., the exact charge distribution in molecules, so they are perfect for the so-called charge control factor of chemical reactions. The energies of the exact upper valence Kohn-Sham orbitals approximate the first ionization energies exceedingly well: whereas the Hartree-Fock orbital energies, within the frozen orbital approxi-mation for ionization energies (Koopmans' theorem), deviate typically more than 1 eV from ionization energies, the exact Kohn-Sham orbital energies have deviations that are typically an order of magnitude smaller. The virtual orbitals of the Kohn-Sham model are not Koopmans-type approximations to the electron affinities, but the virtual-occupied orbital energy gaps are excellent approximations to excitation energies. These are properties that have been the basis for the whole edifice of orbitalbased explanations in chemistry.