Martin Chaplin is an emeritus Professor of Applied Science at London South Bank University. He is a world expert on water science.

Plenary Lecture on : The Science of Liquid Water.

Water only behaves like most other liquids at high temperatures but it is a strange and atypical liquid at lower temperatures. Liquid water is best considered as an intimate mixture of two liquid materials with differing properties; with the amount of each dependent on temperature, pressure, solutes and interfaces. Hydrogen bonding is the cause of these phenomena but confusion still exists over what ‘hydrogen bonding’ in water entails. No longer can we simply describe liquid water in terms of a number of individual water (H₂O) molecules or describe water’s hydrogen bond as simple electrostatic interactions between discrete molecules. We must consider both proton quantum effects and extensive electron delocalization within the network of water molecules as neither the protons nor the electrons are pinned to individual molecules. The science underlying these phenomena and their consequences will be described to hopefully give a better understanding of the material we know as water.