Importance of Water

Describe how hydrogen bonding occurs between water molecules, and relate this and other properties of water, to the roles of water in living organisms.

Water is a very small molecule, consisting of two hydrogen atoms covalently bonded to an oxygen atom. However the electrons shared are not done so equally, oxygen is more electronegative and has a firmer hold on the electrons and pulls them slightly towards its nucleus. Due to this, the charge across the molecule of water is not equally distributed, and the oxygen atom has a partial negative charge whereas the two hydrogen atoms have a partial positive charge, this makes water a polar molecule. The partial charge of oxygen in a water molecule attracts the opposite partial charge in another water molecule which is the positive hydrogen. This constitutes a hydrogen bond which is defined as being a weak interaction between a slightly negatively charged atom and a slightly positively charged hydrogen. Hydrogen bonding is strong enough however to have an effect on physical properties of water and the hydrogen bonding gives water some of its useful properties. Water’s polarity means it is used as a solvent, a substance capable of dissolving other substances, and is specifically good for other polar molecules. The electrostatic attraction between polar water molecules and ions of the opposite charge means that the ions become completely surrounded by water molecules and dissolve. This is the basis for hydrophobic and hydrophilic molecules, polar molecules can interact and are known as hydrophilic, molecules seen as hydrophobic, the non-polar molecules, arrange themselves to expose as little as possible surface area to the water and do not readily dissolve. This enables water to be a good solvent to polar molecules and as most biological reactions take place in solution and as most metabolic processes rely on this factor to enable chemicals to react together, water is seen as being pretty essential. Hence why