Chapter 3 Chem 341 Suroviec Fall 2016

I. Water Nearly all biomolecules assume their shape due to water Polar Molecule Central oxygen forms covalent bonds with two hydrogen atoms, leaving 2 unshared electrons

B. Types of Interactions Non-covalent interactions Ionic Hydrogen-bonds Dipole-dipole Dipole-induced dipole London dispersion

Table 2-1

C. Hydrophobic, Hydrophilic and Amphiphillic Water sticks together Non-polar sticks together Affects entropy Hydrophilic Polar water will dissolve ionic and polar substances Amphophilic Polar and Nonpolar Forms micelles and bicelles

II Properties of Water Polar Molecule High heat of vaporization C. High heat capacity D. High melting/boiling point

III. Chemical Properties Water as a solvent Ability to form H-bonds B. Hydrophobic effect Nonpolar substance does not dissolve but phase separates

IV. Acids, Bases and pH Water ionization 2. pH of a solution

D. Acids, Bases and pH Acid dissociation Base dissociation

D. Acids, Bases and pH 5. pka = -log Ka Acids are classified by Ka Weak acids: Ka < 1 (partially dissociated) Strong acids: Ka >1 (completely dissociated)

D. Acids, Bases and pH Buffers Conjugate acid/base combination that over a small pH range resists changes in pH

D. Acids, Bases and pH