Polarization of ions

It is also interesting to note that metal ions having low polarizability (Al3+ Be2+ etc.) are those that are acidic (as shown in Eq. (9.17)). Also, in Chapter 7 we discussed how the polarization of ions leads to a lattice energy that is higher than that predicted on the basis of electrostatic interactions alone. The polarizability data shown in the table make it easy to see that certain ions are much more polarizable than others. Although we will not visit again all of the ramifications of electronic polarizability, it is a very useful and important property of molecules and ions that relates to both chemical and physical behavior. 

Degrees of Polarity and Mutual Polarization of Ions in the Molecules of Alkali Fluorides, SrO, and BaO... 

A precise quantitative theory of the mutual polarization of ions in molecules is not possible as long as one cannot take into account the inhomogeneity of the field of the polarizing ion and the dependence of the polarizability of the polarized ion on its surroundings. It is therefore attempted to correlate the observed dependence of the p values on r and the polarizability of the ions in a semi-quantitative and semi-empirical fashion. This proves to be successful for the alkali fluorides but explains only qualitatively why the degree of polarity is smaller for BaO than for SrO. 

We arrive at the conclusion that although a precise quantitative theory of the mutual polarization of ions cannot be reached without taking appropriately into account the inhomogeneity of the jrolarizing field and the variability of the polarizabUity of the ions, the discussion in this Sec. 2.3 clarifies semi-quantitatively the factors responsible for the gradation of the degrees of polarity of the alkali fluoride molecules. 

A new theory of electrolyte solutions is described. This theory is based on a Debye-Hiickel model and modified to allow for the mutual polarization of ions. From a general solution of the linearized Poisson-Boltzmann equation, an expression is derived for the activity coefficient of a central polarized ion in an ionic atmosphere of non-spherical symmetry that reduces to the Debye-Hiickel limiting laws at infinite dilution. A method for the simultaneous charging of an ion and its ionic cloud is developed to allow for ionic polarization. Comparison of the calculated activity coefficients with experimental values shows that the characteristic shapes of the log y vs. concentration curves are well represented by the theory up to moderately high concentrations. Some consequences in relation to the structure of electrolyte solutions are discussed. 

The mutual polarization of ions is equivalent to the redistribution of surface charge on the central ion in response to the nonhomogeneous field of the ionic cloud. We need not speculate here on the physical nature of the equipotential surface, except to emphasize that it refers to a solvated species, and one of our... 

The effect of changing the dielectric constant is shown for ions of radius 4.0A in Figure 5, where the values of D correspond to those for the solvents methanol, water, and N-methylpropionamide. The upward turn of log y at higher concentrations is exaggerated when D is low, which is again in qualitative agreement with some experimental observations (2) the effect is attributed to mutual polarization of ions, which is more effective when the permittivity is low. On an intuitive basis it might have been expected, erroneously, that the polarization would lower the activity coefficients, which could be the reason why ionic polarization has received so little attention in interionic theory. 

In addition to these interactions the van der Waals interactions (dispersion forces) between the ions in an ionic molecule or crystal should be considered. This effect has been discussed by M. Born and J. E. Mayer, Z. Physik 75, 1 (1932), and by J. E. Mayer, J. Chem Phys. 1, 270 (1933). Multipole polarization of ions in alkali halcgtmide crystals has been discussed on the basis of a simple quantum-mechanical theory by H. L6vy, thesis, Calif. Inst. Tech., 1938. 

Polar bonds, solid-state materials with. 276-288 Polarizability tensor, 67 Polarization of ions, 129-134... 

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