1. Atoms, Ions and Molecules Properties of Water Acids and Bases Organic Molecules Chemical Reactions Enzymes 1

2. Atoms, Ions and Molecules This topic looks at some Chemistry basics that are essential for understanding life. It defines and explains the roles of atoms, ions and molecules. 2

3. Atoms, Ions and Molecules element - substance that cannot be broken down chemically into any other substances atom - matter that cannot be subdivided any further without losing its essential properties 3

4. Subatomic particles Particles smaller than an atom 1940: protons, neutrons, electrons, neutrinos, positrons Protons, neutrons, electrons – building blocks from which atoms are made protons and neutrons in nuclei electrons in orbit around nuclei Neutrinos and positrons were somewhat peculiar particles discovered outside Earth's atmosphere and of uncertain origin or significance. 4

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10. Atoms, Ions and Molecules Molecule: 2 or more atoms join together chemically Compound: molecule that contains 2 or more different elements All compounds are molecules but not all molecules are compounds. 10

11. Covalent Ionic Polar Covalent Hydrogen 11

12. Covalent Bonds 12

13. Ionic Bonds 13

14. Polar Covalent Bonds electrons shared by the atoms spend a greater amount of time, on average, closer to one nucleus than the other due to geometry of molecule and electronegativity differences 14

15. Polar Covalent Bonds molecule is not an ion (no excess of protons or electrons) water is the most common but not the only molecule that can have polar covalent bonds the biological consequence of polar covalent bonds is that these kinds of bonds can lead to the formation of a weak bond called a hydrogen bond 15

16. Polar Covalent Bonds 16

17. Hydrogen Bonds charged parts of a molecule weak bonds polar covalent bonds can form hydrogen bonds 17

18. Hydrogen Bonds biological systems properties of water proteins and nucleic acids enzyme catalysis 18

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20. What characteristic of an atom gives it its chemical properties? 1. 2. 3. 20

21. All life on earth depends on water; organisms are made up mostly from water and require it more than any other molecule. Hydrogen bonding among water molecules gives water several important properties that contribute to its important role in the biology of all organisms. 21

22. States of Matter 22

23. Cohesion & Adhesion Cohesion – Adhesion – attractive force is what gives water its cohesive and adhesive properties 23

24. Surface Tension cohesion of water molecules 24

25. Cohesion & Adhesion water striders Objects heavier than water, boats floating. 25

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27. Capillary Attraction adhesive properties of water click here for demonstrationhere water 'climbs' up the straw cohesively attracted 27

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29. Low Density as a Solid 29

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31. Why don’t oceans freeze as easily as fresh water lakes? 1. Cohesion 2. Heat capacity 3. Ice floats 4. Water is a good solvent 31

32. Fish live in water. What property of water is important for the survival of fish during the winter? 1. Cohesion 2. Heat capacity 3. Ice floats 4. Water is a good solvent 32

33. Summary – Properties of Water Cohesion Adhesion Surface tension Capillary Attraction High heat capacity Low density as a solid 33

34. Acids & Bases Acid: substance that increases the hydrogen ion (H + ) concentration in a solution Base: substance that removes hydrogen ions from a solution, resulting in an increase in the hydroxide ion (OH - ) concentration. 34

35. Acid H + very reactive Example: H + can bind with atoms in metals, causing them to corrode Acids can donate H + to other chemicals Stomach acid helps to kill most bacteria that you ingest enhances breakdown of chemicals in food enhances efficiency of digestion and absorption 35

36. Bases Low H + ; High OH  Household cleaners Antacids 36

37. Acids & Bases Measurement pH scale very acidic neutral Alkaline (basic) 37

38. pH scale 38

39. Organic Compounds contain carbon chemical compound found in living things Four main types of organic compounds in living things: 39

40. Organic Compounds Combination of carbon and almost any other element atomic structure chains, rings FYI…scientists have already identified more than ten million organic compounds. 40