PROPERTIES OF WATER
Water is a chemical compound of oxygen and hydrogen and in the gaseous state can be represented by the molecular formula H2O. The isotopes of hydrogen and three isotopes of oxygen exist in nature, and if these are taken into account, 33 varieties of water are possible.
The physical properties of liquid water are unique in a number of respects, and these departure from what might be considered as normal for such a compound are of the greatest importance with respect to both the existence of life on earth and the operation of many geochemical processes.
The boiling point and freezing point of water are both far higher than would be the theoretically expected, considering the low molecular weight of the compound, and the range of temperature over which water as a liquid is wider than might be expected. The reason for these and other departures from “normal” behaviour can be gained by more detailed consideration of the molecular structure of the compound.