Supramolecular chemistry

Chapter 3 – Water and the Fitness of the Environment 3.1 – The polarity of water molecules results in hydrogen bonding • Polar molecule – two ends of the molecule have opposite charges • Oxygen: δ- • Hydrogen: δ+ • Positive hydrogen of one molecule is attracted to negative oxygen of another in a hydrogen bond 3.2 – Four emergent properties of water contribute to Earth’s fitness for life • Four properties: cohesive behavior, ability to moderate temperature, expansion upon freezing, versatility as a solvent • Cohesion – the bonding of similar molecules through hydrogen bonds • Adhesion – the clinging of one substance to another • Surface tension – a measure of how difficult it is to stretch or break the surface of a liquid • Kinetic energy – energy of motion