 Biological Hierarchy  Emergent properties  Levels of Biological Organization  Evolution  Universal connection -DNA  Diverse classification of organisms

 Key points Matter- pure form is elements/compounds essential elements trace elements 96% CHON

 Element properties- dependent upon structure  Electron configuration- electrons are involved in chemical behavior  Nuclear structure- isotopes/radioactive isotopes

 Types of bonds in compounds affects properties  Ionic  Covalent: polar/nonpolar  Intermolecular attractions: Hydrogen bonding, dipole-dipole, London Dispersion aka van der Waals forces

 Chemical reactions  Breaking bonds- requires energy  Making bonds –gives off energy  Equilibrium- dynamic reactions- forward and reverse rates become equivalent

 Water- unique molecule due to polarity and hydrogen bonding

 4 important properties of water  Cohesion of water molecules  Moderation of temperature  Solid ice floats on liquid water  Universal solvent

 Overview of Acid/Base Chemistry  Hydrogen ion (H + ) acids  Hydroxide ion (OH - )bases

Water – has dynamic equilibrium in which molecules dissociate at the same rate at which they are being reformed

 A hydrogen atom in a hydrogen bond between two water molecules can shift from one to the other  The hydrogen atom leaves its electron behind and is transferred as a proton, or hydrogen ion (H + )  The molecule with the extra proton is now a hydronium ion (H 3 O + ), though it is often represented as H +  The molecule that lost the proton is now a hydroxide ion (OH – )

 pH- measure of the concentration of H+ ion  pH = - log [H + ]  In aqueous solutions: [OH - ][H + ] =

© 2011 Pearson Education, Inc. Ch. 3 - Water & Life ater & Life For a neutral aqueous solution, [H + ] is 10 –7, so pH = –log [H + ] pH = –(–7) = 7

Figure 3.10 pH Scale Battery acid Gastric juice, lemon juice Vinegar, wine, cola Beer Tomato juice Black coffee Rainwater Urine Saliva Pure water Human blood, tears Seawater Inside of small intestine Milk of magnesia Household ammonia Household bleach Oven cleaner Basic solution Neutral solution Acidic solution Neutral [H + ] = [OH  ] Increasingly Basic [H + ] < [OH  ] Increasingly Acidic [H + ] > [OH  ] H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ OH  H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H

 Buffers  The internal pH of most living cells must remain close to pH 7  Buffers minimize changes in concentrations of H + and OH – in a solution  Most buffers consist of an acid-base pair that reversibly combines with H +

 Buffer in Blood  The bicarbonate ion isn't a very strong acid or base. The direction it goes depends on the solution it is in.

Figure 3.11 CO 2 CO 2 + H 2 OH 2 CO 3 H + + HCO 3  H + + CO 3 2  HCO 3  CaCO 3 CO 3 2  + Ca 2+ H 2 CO 3