1. Chemistry Review AP Biology

2. Chapter 2: The Chemical Context of Life

3. Matter, Elements, and Compounds Matter Anything that takes up space or has mass Element “Pure” substance that cannot be broken down 92 naturally occurring in nature Compound Two or more elements combined in a fixed ratio

4. Life ’ s chemical requirements 25 of 92 elements are required Carbon, nitrogen, hydrogen and oxygen make up 96% of living matter Trace elements Required in minute quantities Some needed by all life forms Others only by certain species

5. Atomic Structure What are these called? These have what charge?

6. Reading the periodic table

7. Isotopes and Radioisotopes Isotopes Different forms of element due to # of neutrons Radioisotopes Nucleus decays spontaneously Date fossils Used to trace atoms through metabolisms Can damage cellular molecules

8. Electron configuration Energy levels Closest shell = least energy Farthest shell = most energy Energy is gained/lost by moving shells Orbital 3-D place where e- are usually found 2 e- per orbital Valence electrons and shell Outermost e- Complete outer shell = non-reactive

9. Chemical Bonding Interactions between atoms Covalent – shared e- Non-polar covalent Polar covalent Ion – charged atom Anion (-) Cation (+) Ionic bond – “steals” e-

10. Weak chemical bonds Hydrogen bonds Hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom Hydrogen bonds, ionic bonds and other weak bonds help form proteins

11. Reactants and Products Chemical reactions Make and break chemical bonds, change composition of matter Reactants and products Starting and ending materials of chem rxns Matter cannot be destroyed, but rearranged Most chemical rxns are reversible Chemical equilibrium When reactions offset one another Rxns still happening, but no effect on reactant/product concentrations Reactants and products are NOT equal in concentration

12. Chapter 3: Water and the Fitness of the Environment

13. Polarity and Hydrogen Bonding Polar molecule Has opposite charges at different ends Each water molecule can bond to a max of 4 others

14. Water Properties and Organisms Water molecules stick together due to hydrogen bonds In liquid form, bonds are fragile Each bond lasts one trillionth a second Cohesion – bonds collectively hold substance together How plants transport water Hydrogen molecules tug on molecules further down the vessel http://faculty.pingry.org/thata/pingry_ upload/movies/water_macromolecul es/cohesion_transport.movhttp://faculty.pingry.org/thata/pingry_ upload/movies/water_macromolecul es/cohesion_transport.mov

15. Adhesion Clinging of one substance to another Surface tension Measure of how difficult it is to break the surface of a liquid

16. Water & Earth Moderates temperatures, contributing to habitability Kinetic energy Energy of motion Heat Measure of total kinetic energy due to molecular motion Temperature Intensity of heat due to avg. kinetic energy Celsius scale

17. Water and Earth, cont. Calorie Amount of heat energy needed to raise 1g of water by 1°C Kilocalorie Amount of heat energy needed to raise 1kg of water by 1°C Joule = 0.239 calories (one calorie = 4.184 J)

18. Water and Earth, cont. Specific heat Amount of heat absorbed or lost for 1g of substance to change 1°C Specific heat of water is 10x that of iron Water resists change in temp High specific heat of water makes ocean temp stable for life Organisms made mostly of water resist temp changes

19. Water and Earth, cont. Liquid molecules moving fast to overcome bonds enter air as gas Vaporization or evaporation Takes 580 calories of heat to evaporate 1g of room temp water Evaporative cooling As substance evaporates, surface of remaining substance cools down

20. Ice Floats Why oceans and lakes don’t freeze Water is less dense as a solid than as a liquid Expands when frozen Reaches its greatest density at 4°C If ice sank, all ponds, lakes, and oceans would freeze solid How would this affect life?

21. Water is the solvent of life Solution Solvent + solute Solvent Does dissolving Solute What dissolves Aqueous solution Solution with water as solvent Water works well, but not for everything, otherwise could not be stored

22. Water is the solvent of life, cont. Hydrophilic Has affinity for water Hydrophobic Repels water Mole Equal in # to molecular weight of substance in grams Molecular weight Sum of all weights of all atoms in a molecules Avagadro’s number = 6.02 x 10 23 (# molecules/mole) Molarity Moles of solute per liter of solution

23. Organisms and pH Organisms are sensitive to pH Hydrogen ion (H + ) single proton with charge of +1 Hydroxide ion (OH - ) charge of -1 Dissociation Transfer of hydrogen atoms

24. pH Acid Substance that increases H + concentration of a solution Donate H + to a solution When hydrochloric acid is added to water HCl  H + + Cl - Base Substance that increases OH - of a solution Concentrations of H and OH Products of OH - and H + concentrations are always 10 -14

25. pH, cont. pH scale Range from 0-14, expresses OH - and H + concentrations Defined as –log[H + ] pH declines as H + concentration increases Each pH unit represents 10-fold difference in OH - and H + concentrations

26. pH, cont. Buffers Substances that minimize changes in pH Accepts and donates ions in solution when needed Ex: carbonic acid

27. Acid Precipitation & Environment Threatens the fitness of environment Acid precipitation Rain, snow, or fog more acidic than pH 5.6 Harms environment by killing plants and animals

28. Chapter 4: Carbon and the Molecular Diversity of Life

29. Carbon Prominent role in evolution of life Can form molecules that are large, complex, and diverse Complexity is demonstrated in hemoglobin

30. Organic Chemistry Study of carbon compounds 30% of a cell is carbon based compounds Common ingredients in carbon compounds: H, O, N, S, P

31. Carbon atoms are a versatile building block Carbon has 6 electrons Little tendency to gain or lose e- and form ionic bonds Completes valence shell by making 4 covalent bonds Makes large, complex molecules possible Carbon is compatible with many different elements CO 2 is the source of carbon for all the organic molecules found in organisms

32. Variation = Diversity Variation in carbon skeletons contributes to the diversity of organic molecules Carbon chains form the skeletons of organic molecules Hydrocarbons Organic molecules consisting only of carbon and hydrogen

33. Variation = Diversity, cont. Isomers Compounds with same molecular formula, but different structures, hence different properties Structural isomers Differ in the covalent arrangements of their atoms

34. Variation = Diversity, cont. Geometric isomers All have same covalent partnerships, differ in their spatial arrangements Stereoisomers Molecules are mirror images of each other

35. Functional Groups Contribute to the molecular diversity of life Hydroxyl group H atom bonded to a O atom, in turn bonded to the C skeleton Alcohol: organic compounds containing hydroxyl groups Polar because of electronegative oxygen Carboxyl O double bonded to a C, bonded to hydroxyl

36. Functional Groups, cont. Amino N bonded to 2 H atoms Sulfhydral S bonded to H Phosphate P ion convalently attached by O atom to C skeleton

38. Chemical Elements of Life: Review Living matter consists of mainly C, H, O Chemical behavior of carbon makes it a versatile building block