Chemistry

1. Chemistry UEQ: What is the relationship between water, the four essential macromolecules and an organism’s regulation by chemical processes? LEQ: How do valence electrons affect living organisms? LEQ: How can I identify an ionic, covalent or hydrogen bonds?

2. 2.1 Everything is made of atoms. • An element is a substance that cannot be broken down chemically into any other substances. • An atom is a bit of matter that cannot be subdivided any further without losing its essential properties.

3. Atomic Structure:The nucleus, protons, and neutrons

4. Atomic Structure: Electrons

5. Atomic Numbers Insert new figure 2.3

6. Isotopes insert new fig 2.4

7. Radioactive Atoms • A few atomic nuclei are not stable and break down spontaneously. • These atoms are radioactive. • They release, at a constant rate, a tiny, high-speed particle carrying a lot of energy.

8. 25 Elements Found in Your Body and the Big 4

9. Take-home message 2.1 • Everything around us, living or not, is made from atoms, the smallest unit into which material can be divided. • Atoms all have the same general structure. • They are made up of protons and neutrons in the nucleus and electrons, which circle far around the nucleus.

10. 2.2 An atom’s electrons determine how (and whether) the atom will bond with other atoms. Electron shells

11. Electron Shells Insert new fig 2-6

12. The Versatility of Carbon Insert fig 2-7

13. Ions Insert new fig 2-8

14. Take-home message 2.2 • The chemical characteristics of an atom depend upon number of electrons in their outermost shells. • Atoms are most stable and least likely to bond with other atoms when their outermost electron shell is full.

15. 2.3 Atoms can bond together to form molecules or compounds.

16. Molecules Products of bonding!

18. Covalent Bonds Insert fig 2-9 to right side of slide

19. Ions and Ionic Bonds Insert fig 2-10

20. Hydrogen Bonds Insert fig 2-11

21. Insert fig 2-12

22. Take-home message 2.3 • Atoms can be bound together in three different ways: covalent bonds, ionic bonds, hydrogen bonds. • Covalent bonds, in which atoms share electrons, are the strongest. • In ionic bonds, one atom transfers its electrons to another and the two oppositely charged ions are attracted to each other, forming a compound • Hydrogen bonds, which are weaker than covalent and ionic bonds, involve the attraction between a hydrogen atom and a polar molecule.

23. 2.4–2.6 • LEQ: How does the arrangement of covalent bonds within a water molecule add to its polarity? • LEQ: How do the special properties of water contribute to Earth’s suitability as an environment for life?

24. 2.4 Hydrogen bonds make water cohesive. Insert fig 2-13

26. Take-home message 2.4 Water molecules easily form hydrogen bonds, giving water great cohesiveness.

27. 2.5 Water has unusual properties that make it critical to life. Cohesion Large heat capacity Low density as a solid Good solvent

28. Cohesion

29. Heat Capacity

30. Why do coastal areas have milder, less variable climates than inland areas?

31. Low Density as a Solid

33. Why don’t oceans freeze as easily as fresh water lakes?

34. Take home message 2.5 The hydrogen bonds between water molecules give water several of its most important characteristics: cohesiveness reduced density as a solid the ability to resist temperature changes broad effectiveness as a solvent for ionic and polar substances

35. 2.6 Living systems are highly sensitive to acidic and basic conditions.

36. Hydrogen Ions and Hydroxide Ions OH - H2O O O H H H Ionized Hydroxide Molecule Non-Ionized Water Molecule

37. pH Scale The amount of H+ in a solution is a measure of its acidity and is called pH. Acids Bases

39. H+ Ions and Acids H+ very reactive Acids can donate H+ to other chemicals Stomach acids

40. Bases Low H+ High OH Antacids Baking soda, seltzer, milk of magnesia

41. Blood pH Buffers can quickly absorb excess H+ ions to keep a solution from becoming too acidic can quickly release H+ ions to counteract any increases in OH concentration

42. Take-home message 2.6 The pH of a fluid is a measure of how acidic or basic a solution is and depends on the concentration of dissolved H+ ions present. The lower the pH, the more acidic the solution Acids, such as vinegar, can donate protons to other chemicals while bases, including baking soda, bind with free protons.

43. 2·7–2·10 Carbohydrates are fuel for living machines.

44. 2.7 Carbohydrates include macromolecules that function as fuel. Health topics of the year Low-carb diet? Hi-carb diet? “Carbo-loading”? Fiber intake? What are carbohydrates?

45. Four Types of Macromolecules Carbohydrates Lipids Proteins Nucleic acids

46. Carbohydrates C, H, and O Primary fuel for organisms Cell structure

47. Energy is in the chemical bonds!

48. Take-home message 2-7 Carbohydrates are the primary fuel for running all cellular machinery and also form much of the structure of cells in all life forms.

49. Take-home message 2.7 Carbohydrates contain carbon, hydrogen, and oxygen, and generally have the same number of carbon atoms as they do H2O units.

50. Take home message 2.7 The C-H bonds of carbohydrates store a great deal of energy and are easily broken by organisms. The simplest carbohydrates, including glucose, are monosaccharides or simple sugars. They contain from three to six carbon atoms.