A singleZ-nucleus, andKelectrons, allow many different, plausible definitions of one-electron energies. The treatment, originally of atomic spectra [of which very high chargesz= (Z - K) now are known], has been extended into chemistry studying a mist of indiscernible electrons around several nuclei. Quantum chemistry has revealed many counterintuitive (verified) consequences, and its Achilles heel is the correlation effect for two-digitZ. The present status of electronegativity, M.O. and inner-shell ionization, stabilization of oxides and of unusual oxidation states, heats of atomization, d and f group characteristics, and spin-pairing energy are reviewed.