The model can be improved in several directions. First, the co-planar assumption of adsorbates and the first water layer can be released by using different planes for them. Second, the effects of the first water layer and adsorbates on 𝜒 M have been neglected. As first water layer and adsorbates modify the electronic structure of the metal surface, 𝜒 M definitely varies, to some extent, for different kinds and coverages of adsorbates and water molecules. Third, in general, 𝛿𝜇 ̃ should be potential dependent as the chemical potential difference between water molecules adopting different configurations must depend on the electrode potential. As a first approximation, one can introduce a linear relationship between 𝛿𝜇 ̃ and the electrode potential. Fourth, more chemisorption processes, including those of electrolyte anions and organic impurities, can be included and their adsorption sites can be differentiated.