The water molecule of life

The water molecule of life
The chemical properties of water have led to the birth and development of life.
The water (H2O) is formed of an oxygen atom bonded to two hydrogen atoms by links
covalent (Figure 1A). This molecule is stable, does not net electrical charge and is
capable of forming weak chemical bonds with different compounds.
The main properties of the water has allowed the development of life can be summarized as follows.
• The polarity of the water molecule, that is to say the fact that it is the dipoles positive and negative
distributed asymmetrically, can form weak hydrogen bonds (Figure 2B).
Thus, water can act as an electron donor and allow the reactions
hydrolysis. This property is involved, both in the temporary connection of a molecule
organic, in that the cohesion of the water in the liquid state (surface tension).
• The polarity of the water also that its molecules are attracted to other molecules with
electrical charges. Thus, crystals of molecules, even weakly charged, may
dissolve readily in water, whose molecules are then form a "crown
hydration "preventing re-formation of the crystal (Figure 2C). In contrast, this property
excludes non-polar molecules such as oil, forcing the latter to adopt certain
conformations (Figure 2D).
• The specific heat and heat of vaporization of water is high. Thus, water heaters difficult,
but keeps the calories stored. This property allows in particular to "stamp
"The temperature changes within the body, following the chemical reactions that
occur there. Moreover, the vaporization of water requires much energy, it allows
effectively cool the body surface of animals during sweating.