AT MOST, ONLY ONE-ELECTRON CAN BE ADDED TO A FREE ATOM IN GAS-PHASE

A quantitative relation between static electric dipole polarizability and ionization potential of an atomic species with some amount of char ge is derived semiempirically to argue that to any free neutral atom, not more than one electron can be added in the gas phase to produce a thermodynamically stable anion. Experimentally, the argument does not hold in some closed shell neutral atoms, where addition of even one el ectron gives rise to thermodynamically unstable species.