The strength of their interactions drops drastically as soon as angles appear between the affected groups. The length of hydrogen bonds depends on the type of the involved groups and is between 2.7 and 3.1. The shape of the molecule and the structure of the weak interactions cause the crystal structure of ice and even in liquid state exists still a high degree of order with the water molecules arranging in the form of micelles . This explains why ions detach themselves so much easier from their crystal structure in water than in air. The thermally caused molecular movements at room temperature are thus sufficient to overpower the relatively weak attractions of the ions within the crystal and to let them dissociate into the aqueous medium.
Water molecules display a strong tendency to form shells of hydration .
In this way do they shield ionic charges and neutralize them partially. Water molecules orient themselves within the electrostatic field and are thus immobilized. Van der Waals attractions is the term used for non-specific attractions between two atoms that are close to each other. Consequently are Van der Waals attractions under physiological conditions only of importance, if as many atoms of a molecule as possible are engaged. They are strongest, if the involved molecular structures complement each other.