In the H2O molecule, the single electron of each H is shared with one of the six outer-shell electrons of the oxygen (creating two covalent bonds), leaving four electrons which form two non-bonding pairs. It is the way in which the size and nuclear charge of the oxygen atom works to distort the electronic charge clouds of the atoms of other elements, when these are chemically bonded to the oxygen that gives water so many of its unique properties.
Liquid water is much more than millions of discrete H2O molecules. It is actually a highly mobile, vibrating and forever changing cluster of water molecules where the hydrogen bonds between individual water molecules are continuously breaking and reforming.
We know that water structure, or the arrangement of the molecules in a given volume of water, varies according to many factors including temperature and pressure. We also know that the structure and properties of water within cells, particularly adjacent to membranes in cells or organelles (sometimes referred to as vicinal water), is very different to the structure of bulk water. The key point here is that the unique structure of water within cells is purely a result of the geometry of the surrounding hydrogen bonding sites.
