Tetrahedral bonding, water molecules

This is very difficult to explain other than in terms of hydrophobic hydration, that is, cage formation of tetrahedrally H-bonded water molecules around the solute. Forming the cage in water with the apolar molecule inside corresponds to an increase in entropy compared with the simation of the apolar molecule in other solvents. 

Ionic solutes are hydrated as a consequence of attractive electrostatic interactions between the charges on the ions and the dipoles of the water molecules. These interactions break down the tetrahedral arrangements of H-bonded water molecules near the ion to form a spherically symmetrical hydration shell which is not H-bonded in the pattern characteristic of the pure solvent. 

Photo 38 Linus Pauling lecturing on hydrogen bonding and ionic hydration, ca. 1975. In the upper right comer of the blackboard is the statistical factor (3/2), which is the basis of Pauling s famous calculation of the residual entropy of ice (SP 73). To the left of (3/2) is depicted a tetrahedrally coordinated water molecule. 

We will call a hexacycle stracture constructed only of twist-boats connected with each other as th-cycle [18], The th-cycle is a system of cycles that are built of tetrahedral particles (water molecules connected by H-bonds). The tetrahedral particles are arranged in a twist-boat hexacycles of the same chirality. The twist-boats are linked with each other in special way [18] and form a th-cycle. The main characteristics of th-cycle are ... 

Figure 12 An illustration of the tetrahedrical surroundings of a hydrogen-bonded water molecule in liquid water. 

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