Page 216 - MODERN ELECTROCHEMISTRY

152 CHAPTER 2

The key to understanding this surprising result is the interplay between the 4p and
the 4s orbitals. The latter can mix in 4p character with its shoelace shape. Such an
orbital (effectively an electron cloud) reduces the repulsion between water molecules
1 and 2. Such a reduction allows the bonding energy of the second water to be greater
than that of the first. The degree of this mixing of 4p character into 4s (and the resulting
effect on bonding) depends on the ion. If the effect is small, repulsion between water
molecules 1 and 2 remains great enough for the second water to have a lesser bonding
energy than the first, as would ordinarily be expected.

Further Reading

Seminal
1. D. D. Eley and M. G. Evans, “Statistical Mechanics in Ionic Solutions,” Trans. Faraday
Soc. 34: 1093 (1938).
2. S. Lee and M. Tai, “Individual Ionic Entropy of the Proton,” J. Chinese Chem. Soc. 9: 60
(1941).
3. F. H. Halliwell and N. C. Nyburg, “Hydration Heat of the Proton,” Trans. Faraday Soc.
59: 1126 (1963).
4. J. O’M. Bockris and P. P. S. Saluja, “Model-Based Calculations of Hydration Energies,”
J. Phys. Chem. 76: 2295 (1972).
5. B. E. Conway, “Individual Ionic Properties,” J. Solution Chem. 7: 721 (1978).
6. P. Kebarle and E. W. Godbole, “Hydration in the Gas Phase,” J. Chem. Phys. 39: 1131
(1983).

Reviews
1. R. R. Dogonadze, A. A. Kornyshev, and J. Ulstrup, “Theoretical Approaches to Solvation,”
in The Chemical Physics of Solvation,R. R. Dogonadze, E. Kalman, A. A. Kornyshev,
and J. Ulstrup, eds., Part A, Elsevier, New York (1985).
2. G. A. Krestov, “Individual Ionic Properties,” in Thermodynamic Structure of Solvation,
Ellis Harwood, New York (1990).

Papers
1. R. C. Keese and A. W. Casheman, J. Am. Chem. Soc. 14: 9015 (1989).
2. J. Marinelli and R. R. Squires, J. Am. Chem. Soc. 111: 4101 (1989).
3. M. Rosi and C. W. Bauschlicher, J. Chem. Phys. 90: 7264 (1989).
4. R. S. Drago, D. C. Feris, and N. Wang, J. Am. Chem. Soc. 112: 8953 (1990).
5. A. D. Paynton and S. E. Feller, J. Electrochem. Soc. 137: 183 (1990).
6. A. G. Sharpe, J. Chem. Ed. 67: 309 (1990).
7. S. Golden and T. R. Tuttle, J. Phys. Chem. 95: 4109 (1991).
8. H. Mizuno and M. Sakiyami, J. Phys. Chem. 95: 2536 (1991).
9. T. F. Magnera, D. E. David, and J. Mich, Chem. Phys. Lett. 182: 363 (1991).
10. P. M. Quereschi, S. Kamoonpuri, and M. Igbal, J. Chem. Ed. 68: 109 (1991).