polar, covalently bonded atoms

weakens electrostatic interactions due to high dielectric constant

2 long pairs of e-

forms hydrogen bonds (is a H bond donor & acceptor)

Hydrogen Bonding

direction?

electrostatic : covalent ?

Other properties?

highly directional (linear is strongest)

90% electrostatic/10% covalent

High melting pt, boiling pt, heat of vaporization

Water can form 4 H bonds @ once, bc H bonds are dynamic (constantly breaking & forming)

Hydrophobic Effects

Important in Protein folding & lipid-lipid interaction

(Polarity)

Not caused by hydrophobic molecules interacting strongly, but by water interacting strongly!!

Water binds strongly to itself, loss of entropy due to ordering.

Hydrophobic interactions are a factor in micelle formation

Decreases surface area when nonpolar molecules are clumped.

[ concentration ] high or low, inside or outside?

Isotonic

Hypertonic

Hypotonic

Kw = [H+][OH-] = 1*10^(-14)

Increase in [H] causes decrease in [OH]

pH = log (1/[H+]) = -log [H+]

= pKa + log ( [A]/[HA] )

1 pH unit = 10 times [H+]

Strong Acids

Strong Bases

Ionize completely in aqueous solution

Mineral acids (HCl, HNO3, H2SO4)

Bases (NaOH, KOH)

Weak acids

Weak bases

do not ionize completely

Ka = ( [H][A] ) / [HA]

pKa = -log Ka

Increasing Ka = Increasing Acid strength = Decreasing Base strength

Polar

Nonpolar

Amphipathic

Polar: central atom, surrounding atoms are *the same*, hydrophillic.  SH2, NH3

Nonpolar: no central atom, hydrophobic, no charges.  N2, O=O

Amphipathic: contains both polar & nonpolar regions