1. Chemistry for Living Things Chapter 2

2. 2.1 Composition of Matter Matter – anything that takes up, or occupies space….and has mass! Mass – amount of matter in an object Mass and Weight are not the same!!!!!!! The pull of gravity on an object gives it its weight. You would have the same mass here and on the moon……but different weights due to gravity.

3. Elements Fundamental forms of matter - cannot be broken down chemically Substances that are made up of 1 type of _______________ 100 elements have been identified 92 occur naturally on Earth Others are man-made

5. HYDROGEN HELIUM Hydrogen and Helium Atoms electron proton neutron

6. 1) 2) 3) ------ Atomic # ------- Element -------Atomic mass aka Mass # 11 Sodium 22.93~ 23 How many Electrons? How many Protons? How many neutrons? 19 Potassium 39.098~ 39 ------ Atomic # ------- Element -------Atomic mass aka Mass # ------ Atomic # ------- Element -------Atomic mass aka Mass # 17 Chlorine 35.453~ 35 11 11 23= N + 11 N= 12 19 19 39= N + 19 N= 20 17 17 35=N+17 N=18

7. BOHR MODEL Main Points of the Bohr Model Electrons orbit the nucleus in orbits that have a set size and energy. The energy of the orbit is related to its size. The lowest energy is found in the smallest orbit. Radiation is absorbed or emitted when an electron moves from one orbit to another.

8. Show a Bohr Model for: Carbon (#6, mass12) Sodium (#11, mass 22.9) Oxygen (#8, mass 15.99)

9. Molecules Elements Atoms Subatomic particles Diatomic OR Compound

10. Important Bonds Ionic Bonds - arrow Covalent Bonds – strongest, circle Polar covalent – H2O Hydrogen Bonds - weakest

11. What is an ION? A CHARGED atom or particle + - cation anion

12. Ionic Bonding when you: __________ electrons, becomes positively charged ion _____________ these electrons, becomes negatively charged ion Charge difference attracts the two ions to each other Ever hear the phrase “Opposites Attract”…… If atom loses If atom gains

13. Formation of NaCl Sodium atom (Na) –Outer shell has one electron Chlorine atom (Cl) –Outer shell has seven electrons Na transfers electron to Cl forming Na + and Cl - Ions remain together as NaCl-- diatomic or compound

14. Covalent Bonding Atoms share a pair or pairs of electrons to fill outermost shell CSharing is Caring

15. Try to draw the Formation of NaCl with either the Lewis Dot or Bohr……

16. Show a bond between carbon(#6,mass12) and hydrogens (#1,mass1)

17. Enzymes -Enzymes are proteins that catalyze (Increase rates of) chemical rxn by lowering the activation NRG -Almost all chemical reactions in a biological cell need enzymes in order to occur at rates sufficient for life.biological cell -What do they DO: lowering the activation energyactivation energy As a result, products are formed faster and reactions reach their equilibrium state more rapidly. -Can they be affected: YUP! -Inhibitors -Concentration -Temperature

19. 2.3 SOLUTIONS What do you think of when you think “solution” ? –All living things are made mostly of water/blood = LIQUID in which chemical reactions take place

20. -two or more materials mixed or stirred together -CAN be separated easily -2 types:

21. -A mixture in which one or more substances are uniformly distributed in another substance Made up of: -SOLUTE – substance ___________________ the solution -SOLVENT – substance in which the __________________________________

23. Why is Water a good Solvent? Because of it’s polarity (charged atoms), it wants to combine to almost anything in it !

24. Saturated Solution Type of solution in which no more ________________________________ Eg. Sugar at the bottom of drinks

25. Concentration amount of solute dissolved in a solution (High or Low) mg/mL -Remember the cool-aid from lab

26. Meet THESE ions: The HYDROXIDE ion OH- H 2 O  H+ + OH- The HYDRONIUM ion H 3 O+ H 2 O + H+  H 3 O+ How can water form these? Splitting H20 into ions (boil)

27. The pH Scale Measures ______ concentration of fluid Change of 1 on scale means 10X change in H + concentration Going from a pH of 3 to pH of 5 would be 100X, 3  6, 1000X Highest H + Lowest H + 0---------------------7-------------------14 Acidic Neutral Basic

28. Acids & Bases pH of 7 = neutral: H 3 O + = OH – ACIDS: Donate H + when dissolved in water H 3 0 + (hydronium) greater than OH - (hydroxide) Acidic solutions have a pH < 7 BASES: Accept H + when dissolved in water OH- (hydroxide) greater than H 3 O + (hydronium) Basic (alkaline) solutions have pH > 7

29. Examples of pH Pure water is neutral with pH of 7.0 Acidic –Stomach acid: pH 1.0 - 3.0 –Lemon juice: pH 2.3 Basic –Seawater: pH 7.8 - 8.3 –Baking soda: pH 9.0

30. Acids & Bases Acids –Donate H + when dissolved in water –Acidic solutions have pH < 7 Bases –Accept H + when dissolved in water –Alkaline solutions have pH > 7

33. Buffer Systems Minimize shifts in pH Partnership between weak acid and base it forms when dissolved Two work as pair to counter shifts in pH Jelly fish stings are basic.

34. Salts Compounds that release ions other than H + and OH - when dissolved in water Example: NaCl releases Na + and Cl – Many salts dissolve into ions that play important biological roles

35. 3.1 WATER “WADER” Do now: draw Bohr model of H2O and tell how the Hydrogens bond with the oxygen

36. 3.1 WATER H2O

37. Structure of WATER ___ Hydrogens, ___ Oxygen Covalently Bond O has a slightly negative (-) charge H have a slightly positive (+) charge

38. Water Is a Polar Covalent Molecule Molecule has no net charge BUT Oxygen end has a slight negative charge Hydrogen end has a slight positive charge

39. Polarity – uneven charge When the # of protons in two nuclei is NOT the same, ____________ spend more time near nucleus with most protons Water - electrons more attracted to ____ nucleus than to _____ nuclei O H

40. 6P

41. O H H O H H + _ + + + _ + + Hydrogen bonds hold Liquid Water together

42. Hydrogen Bonding - the force of attraction between: a Hydrogen with a + charge AND another atom/molecule with a - charge - H bonds form, break and reform with great frequency and ease (weak bonds)

43. one large molecule another large molecule a large molecule twisted back on itself Fig. 2.12, p. 27 Examples of Hydrogen Bonds

44. Hydrogen Bonding holds DNA strands together

45. Atom in one polar covalent molecule can be attracted to oppositely charged atom in another such molecule

46. Properties of Water Polarity Temperature-Stabilizing Cohesive Solvent Makes Ions

47. Water Is a Polar Covalent Molecule Molecule has no net charge Oxygen end has a slight negative charge Hydrogen end has a slight positive charge O HH

48. Temperature-Stabilizing Effects Liquid water can _____________________ before its temperature rises Why? Much of the added energy disrupts hydrogen bonding rather than increasing the movement of molecules

49. Evaporation of Water Large energy input can cause individual molecules of water to break free into air As molecules break free, they carry away some energy (lower temperature) Evaporative water loss is used by mammals to lower body temperature

50. Hydrophilic & Hydrophobic Substances Hydrophilic substances –Polar –Hydrogen bond with water –Example: sugar, salt Hydrophobic substances –Nonpolar –Repelled by water –Example: oil

51. Water Is a Good Solvent Ions and polar molecules dissolve easily in water When solute dissolves, water molecules cluster around its ions or molecules and keep them separated

52. Fig. 2.16, p. 29 Na + Cl – – – – – – – – – – – – + + + + + + + + + + + + + + + + + + Spheres of Hydration

53. Water Cohesion/Adhesion Hydrogen bonding holds molecules in liquid water together (cohesion) and also attracts to other surfaces (adhesion) Creates tension

57. Explains how water defies gravity and travels upwards in plant stems! Moving up through narrow tubes against the force of gravity is called _______________

58. Why Ice Floats In ice, hydrogen bonds lock molecules in a ________________________ (spread out solid formation) Water molecules in lattice are spaced farther apart then those in liquid water Ice is _____________ dense than water

60. Hydrogen Ions: H + Unbound protons Have important biological effects Form when water ionizes

61. Ionization of Water H 2 O + + H 2 O HYDROXIDE! HYDRONIUM

62. 1. Describe the structure of a water molecule 2. How does polar differ from nonpolar? P- UNEVENLY CHARGED, NP- EVENLY CH. 3. what happens when ions are mixed with water? They DISSOLVE (attacked by opposite charged H2O 4. what are 2 properties of water that are caused by hydrogen bonding? COHESION, ADHESION 5. what is capillarity? Ability of water to move up a small tube (stem) 6. water is used to cool a car’s engine. Explain a certain property of antifreeze that can replace water. It takes a longtime b4 it heats up