Specific dipolar, acid-base and charge interactions involve electron displacements. For atoms, single bonds andmolecules electron displacement is characterized by electronic potential, absolute hardness, electronegativityand electron gap. In addition, dissociation, bonding, atomization, formation, ionization, affinity and latticeenthalpies are required to quantify the electron displacement in solids. Semiconductors are characterized byvalence and conduction band energies, electron gaps and average Fermi energies which in turn determineGalvani potentials of the bulk, space charge layer and surface states. Electron displacement due to interactionbetween (probe) molecules, liquids and solids are characterized by parameters such as Hamaker constant, solubilityparameter, exchange energy density, surface tension, work of adhesion and immersion. They are determinedfrom permittivity, refractive index, enthalpy of vaporization, molar volume, surface pressure andcontact angle. Moreover, acidic and basic probes may form adducts which are adsorbed on target substrates inorder to establish an indirect measure of polarity, acidity, basicity or hydrogen bonding. Acidic acceptornumbers (AN), basic donor numbers (DN), acidic and basic “electrostatic” (E) and “covalent” (C) parametersdetermined by enthalpy of adduct formation are considered as general acid-base scales. However, the formalgrounds for assignments as dispersive, Lifshitz-van der Waals, polar, acid, base and hydrogen bond interactionsare inconsistent. Although correlations are found no of the parameters are mutually fully compatible andmoreover the enthalpies of acid-base interaction do not correspond to free energies. In this review the foundationsof different acid-base parameters relating to electron displacement within and between (probe) molecules,liquids and (semiconducting) solids are thoroughly investigated and their mutual relationships are evaluated.
- ACID-BASE BALANCE