1. Properties of Water Biochemistry

2. Why is Water Important? Habitat Transport medium Some metabolic reactions Cell shape homeostasis

3. Chemistry of 1 Water Molecule Covalent bonds – formed when two atoms share electrons (H and O) – Strong bonds Water molecule = neutral molecule – Electron # - proton # Water is polar – Not sharing electrons equally – Oxygen has a stronger pull on shared electrons

4. Chemistry of Many Water Molecules Attraction between Hydrogen and Oxygen on different molecules = hydrogen bonds – Weak bonds 1 water molecule can H- bind with 4 other water molecules Many water molecules together = network

5. Properties of Water 1. Excellent solvent (can dissolve many substances) Hydrophilic substances can dissolve (ex. salt) – Polar Hydrophobic substances cannot dissolve (ex. oil) – Nonpolar

6. Properties of Water 1. Stabilizes temperature Lots of energy needed to raise temperature H-bonds need to be broken for molecules to move (movement = raise in temperature) Maintaining homeostasis

7. Properties of Water Cohesion = water sticks to itself – Surface tension Adhesion = water sticks to other substances Capillarity = movement of water against gravity 3.

8. Properties of Water Water expands when frozen Solid ice = less dense then liquid water – Ice floats