acids/bases

• Lewis acids

  • electron acceptors
  • electrophiles
  • want electrons
• Lewis bases

  • electron pair donator
  • nucleophile
  • electron rich
• Bronsted-Lowry acid

  • donate H+
  • has an H
• Bronsted-Lowry base

  • H+ acceptor
  • Sometimes electronegative
• Bronsted-Lowry acids/bases

  • proton based, proton transfer H+
  • can react with water
  • acidity determined with electronegativity but in the same period the lower element is considered more acidic
  • equilibria
  • an electron pair displacement reaction
• Bronsted-Lowry acid/base strength

  • stronger acid that loses H+ becomes a weak conjugate base
  • conjugate acid of a strong base is a weak acid
  • pka values determine strength
  • lower the pka of an acid the stronger the acid
  • lower the pka of a base the weaker the base
  • equilibrium always favors the formation of the weaker acid and weaker base
• Finding acidity (BL)

  • element effect: what H is directly attached to in relation to P.T.
  • inductive effect (or polar effect): acidity increases with more electronegative elements
  • resonance effect: conjugate bases are resonance stabilized (or considered to be same no major/minor)
  • hybridization: increasing s character, increasing acidity (+ not applicable)
• electron pair sharing vs. displacement

  • sharing: bond formation between two molecules, 2 reactant --> one product
  • displacement: removes part of molecule and attaches to another using electrons (not proton H, has to be electrons)
  • ex d: CH3Br + OH- --> CH3OH + Br-
• amphoteric compounds

  • compounds that behave as either BL acids or bases
  • must have proton H
  • must be electronegative
  • For LA/B: must have an electron pair, but also willing to accept electrons