1. Water – Part I CHEM 7784 Biochemistry Professor Bensley

2. Chapter 2.1 Weak Interactions in Aqueous Solutions –What kind of interactions occur between molecules –Why water is a good medium for life –Why nonpolar moieties aggregate in water –How dissolved molecules alter properties of water Today’s Objectives: to understand

3. Structure of the Water Molecule

4. Crystal lattice of ice One H 2 O molecule can associate with 4 other H 2 0 molecules Ice: 4 H-bonds per water molecule Water: 3.4 H-bonds per water molecule Hydrogen Bonding in Water

6. Hydrogen Bonds

7. Hydrogen Bonds: Examples

8. Biological Relevance of Hydrogen Bonds

9. Examples of Noncovalent Interactions

10. The Hydrophobic Effect

14. Van der Waals Interactions

15. Water as a Solvent Water is a good solvent for charged and polar substances Water is a poor solvent for nonpolar substances

16. Water Dissolves Many Salts

17. Solubility of Polar and Non- polar Solutes Why are non-polar molecules poorly soluble in water?

18. Colligative Properties

19. Effect of Extracellular Osmolarity