Water
- Water molecules consist of 2 hydrogen molecules covalently to an oxygen molecule.
- The molecules are slightly polar because the oxygen nucleus pulls the shared electrons away from the hydrogen nuclei. Giving the oxygen nuclei a δ- charge, and the hydrogen nuclei a δ+ charge.
- The polarity of water causes attraction between water molecules. This force of attraction is called a hydrogen bond.
Property of Water | Why is it useful |
Liquid medium | Provides habitats for aquatic organisms, medium for chemical reactions & used for transport |
Important metabolite | Used in hydrolysis & condensation reactions |
High specific heat capacity | Keeps aquatic & cellular environments stable |
High latent heat of vaporisation | Evaporation has a cooling effect on organism |
Cohesion of molecules | Water is drawn up the xylem |
Surface tension | Allows pond-skaters to walk on the surface |
Good solvent and transport medium | Dissolves ionic and polar molecules, allowing them to easily be transported |
Good reaction medium | The cytoplasm in cells is an aqueous solution where many chemical reactions happen |
Incompressible | Can prevent plants from wilting & act as a hydrostatic skeleton for invertebrates |