Chemistry of Life: Elements, Bonds, and pH

1. Chemistry of Life Ch. 2 and 3

2. If you tear paper in half, and keep tearing the halves into halves, will you always have paper left?What is the smallest unit eventually left?

5. Elements in the Body • What elements do you think are the most abundant? • O,H, C and N • What do you think a trace element is? • Trace elements in the body are Selenium, Mercury, Arsenic and Lead. • All of the elements in the human body could be bought for $118.63.

12. H2O + 1/2 O2 H2O2

13. Photosynthesis Captures energy Chloroplasts in plants 6CO2 + 6H2O  C6H12O6 + 6O2 Cellular Respiration Releases energy Mitochondria C6H12O6 + 6O2  6CO2 + 6H2O Photosynthesis vs. Cellular Respiration What do you notice about these two equations? 1.3, 1.4, 1.9, 1.43

16. Some isotopes are radioactive. They are used for determining ages of fossils. They are also used in medicine. to treat cancer or as tracers. PET scans Ie. 12C- non radioactive (6p+, 6 neutrons) 14 C- Radioactive (6 p+, 8 neutrons) (protons and electrons stay the same, the neutrons are different. If you add the p+ and neutrons you get 12 or 14.) Isotopes

17. Energy Levels • 5 levels : K: n=1, L: n=2, M: n=3, N: n=4, O: n=5 • 2n2 tells the number of electrons you can have in each level (orbitals) • Valence e-, located in outer shell. • Ideally, shell wants to be full. Most you can have in an outer shell is 8. • Electrons can move or jump to other levels.

19. Electron Configurations • I will help you write the electron configuration for Lithium and Nitrogen. • 1st: find number of electrons • 2nd: write out 1s, 2s, 2px, 2py, 2pz, 3s, etc. • 3rd: Show where you put electrons, one at a time in each orbital. • 4th: Write the configuration. • You try Magnesium • Li: 1s22s1 • N: 1s22s22p3 • Mg: 1s22s22p63s2

20. Chemical Bonds • Atoms with unfilled orbitals in their outermost shell tend to be reactive with other atoms.

21. Van der Waals, H bonds

22. Bonding Link

24. Van der Waals- slight attraction between oppositely charges regions of molecules. They can hold large molecules together. Gecko’s feet Hydrogen bonds- an atom of a molecules interacts weakly with a H atom already taking part in a polar covalent bond. Holds together N bases on DNA. Weaker Bonds

26. How are molecules different from compounds?

27. Covalent Bonds • Non-polar: atoms share electrons equally • Polar: share atoms unequally making a slight difference in charge between the two poles of the bond.

28. Sometimes covalent bonds do not share electrons equally. Some atoms in the molecule have a slightly negative charge and others have a slightly positive charge. Polar: hydrophilic Nonpolar: hydrophobic Water Link Water molecule. NH3 How do you know it’s polar? Polar Molecules (-) O H H (+) (+) .

29. Water’s Temperature-Stabilizing Effects • Water tends to stabilize temperature because it can absorb considerable heat before its temp changes. • Evaporation- H bond break • Freezing- H bonds resist breaking

30. Cohesion Hydrogen Bonding causes water molecules to stick together, producing surface tension. Adhesion- sticks to something else. Water Expands when it Freezes Ice Floats because it is less dense than the water. Features of Water

31. Mixture- material composed of two or more elements or compounds that are physically mixed together but not chemically combined. Salt and pepper, sugar and sand, etc. Solution- well mixed mixture. Where all components are evenly distributed. Give an example. Solutions

33. Suspensions Mixtures of water and non-dissolved materials. Can you give any examples? Common suspensions include sand in water, fine soot or dust in air, and droplets of oil in air.

34. Can you explain this? Can you give any examples of this? What do you know about pH? 1.5 Most cells have a narrow range of temperature and acidity that they can survive. If there are extreme changes in the environment, they may alter the structure of the protein and the cells function.

35. pH • Measure of H+ concentration in a solution. The greater the H+ the lower the pH scale. • Acids- releases H+ • Bases- release OH-

38. Scales of 10. Ie. A pH of 4 would have 10 more H+ than a pH of 5. Animated pH scale

40. Salts • Salt is any compound that dissolves easily in water and releases ions other than H+ and OH-. • Ionic compound formed when an acid reacts with a base. • HCl + NaOH  NaCl + H2O • Salts dissociate into useful ions in the body (Na+ and Ca++).

41. Weak acids and weak bases that react with strong acids or bases to prevent sharp, sudden changes in pH. Control pH to maintain homeostasis. Buffers Hemoglobin (carries oxygen) maintains a stable pH in red blood cells (RBC). Bicarbonate is a body buffer.

42. Buffer control (equations go both ways) HA + H2O  A- + H3O+ Weak acid + water  conjugate base + hydronium HA + NaOH  Na+A- + H2O A- + HCl  HA + Cl-

43. Homeostasis in your body • Blood pH must be between 7.3-7.5 • If blood pH increases to 7.8, • tetany may occur where skeletal muscles cannot be released from contraction. • Alkalosis can be lethal (blood pH rises and is not reversable). • If it falls to 7, the person could go into a coma • Respiratory acidosis- too much CO2 forms too much carbonic acid and pH drops.

44. Molecules of Life Ch. 3

45. 1.4 The work that takes place in the cell is carried out by the different types of molecules it assembles: proteins, lipids, carbohydrates, and nucleic acids.

46. Carbon C Hydrogen H Nitrogen N Oxygen O Phosphorus P Sulfur S Carbon can join to other carbon atoms in chains and rings to form large complex molecules. 1.6 Cells are made up primarily of a small number of chemical elements

47. Carbon’s bonding behavior • Can form 4 covalent bonds. • Functional groups are atoms or groups of atoms covalently bonded to a C backbone, giving distinctive properties to the molecule.

48. Functional Groups • Hydroxyl -OH • Methyl -CH3 • Carbonyl - CO (Ketone- inside) or CHO (aldehyde- end) Carboxyl -COOH (non-ionized) or COO- (ionized) Amino -NH2 (non-ionized) or –NH3+ (ionized) Phosphate - PO4 or - P

49. Where found

50. Methane • In methane seeps, methane bubbles upward from ocean floor. • Archaea use methane as energy source and release CO2 and H2 . • Bacteria around them use the H2 and made H2S using sulfate in water.