Liquid water (H2O) is the most remarkable substance. However, it is often perceived to be pretty ordinary. We wash in water, fish in water, swim in water, drink water and cook with water, although probably not all at the same time. We are about two-thirds water and require water to live. Life as we know it could not have evolved without liquid water and dies without it. Droughts cause famines and floods cause death and disease. Because of its clear importance, water is the most studied material on Earth. It comes as a surprise, therefore, to find that liquid water's behavior and function are so poorly understood, not only by people in general, but also by scientists working with it everyday.
Water seems, at first sight, to be a very simple molecule, consisting of just two hydrogen atoms attached to an oxygen atom. Indeed, there are very few molecules that are smaller.
The size of the water molecule, however, belies the complexity of its properties and these properties seem to fit ideally into the requirements for life as can no other molecule.
A number of explanations of the complex behavior of liquid water have been published, many quite recently. In this site, I have brought together a self-consistent selection of these ideas, which I hope will encourage both the understanding of water and further work.
Water (H O) consists of an oxygen atom covalently bonded to two hydrogen atoms. A huge amount of energy is needed to overcome the forces of attraction between the water molecules, allowing them to move about and change from solid to liquid and from liquid into gas. The properties of water result from the molecule having electron-rich and electron-poor regions, which gives it partially positive and partially negative poles. Water begins to freeze at 0°c and boils at 100°c. Water has the highest known specific heat, and acts as an efficient solvent, particularly when hot. It needs a lot of heat add