Structure and Properties of Water in its Various States

Abstract

Abstract Water is a unique substance with properties that are not predictable from those of other materials. It has a complex phase space where all of its physical and structural forms possess unexpected properties. Mostly, these are consequences of the ability of the water molecule to form strongly hydrogen‐bonded intricate structures. The extensive hydrogen bonding provides water with the ability to transfer protons and electrons rapidly between the water molecules and to produce positively charged hydrogen ions and negatively charged hydroxide ions. In the many solid phases, each water molecule forms exactly four hydrogen bonds in a tetrahedral arrangement with two hydrogen atoms near each oxygen atom. This arrangement is also present, if much more loosely, in liquid water, where the overall structuring is far more complex. Such liquid water behaves as though it is a mixture of two liquids that change relative composition with variations in temperature and pressure. The properties of liquid water are particularly affected at low temperature when supercooled and at very low temperatures when water glasses are formed. Even gaseous water is affected by this hydrogen bonding.