 Needham (2000) and van Brakel (2000) have argued that compounds such as water are dynamic structures whose natures cannot be given in static accounts of their composing elements. Molecules of H2O are polar, with the consequence that the electropositive hydrogen atoms in one H2O molecule will bond with the electronegative oxygen atoms in another H2O molecule, such bonds being hydrogen bonds with the result that in liquid water H2O molecules will form polymer-like chains known as oligomers. The hydrogen bonds and the consequent chains are responsible for the fact that water is liquid at room temperature (whereas compounds with similarly sized molecules, such as hydrogen sulphide, methane, and carbon dioxide, are all gaseous at room temperature). These oligomers are constantly forming, breaking, and reforming. The rate of such changes and the mean length of such oligomers are dependent on the thermodynamic context (in the extreme case, an ice crystal may be considered as a single such oligomer, the crystal structure being dependent on the fixed, strong hydrogen bonds). Thus, say Needham and van Brakel, we cannot consider water to be just a compound composed of a collection of H2O molecules. Furthermore, anything that is to be water must be a macroscopic entity, since only macroscopic bodies can bear thermodynamic properties, such as melting point, which we use to identify water. Hence, a single H2O molecule is not water.