Unit 2:Chemistry of Life

1. Unit 2:Chemistry of Life Atoms, Ions and Molecules Properties of Water Acids and Bases Organic Molecules Chemical Reactions Enzymes

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.

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

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.

6. “CHONPS” + 4

7. “CHONPS”

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.

11. Chemical BONDS • Covalent • Ionic • Polar Covalent • Hydrogen

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

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

16. Polar Covalent Bonds

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

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

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

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.

22. States of Matter

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

24. Surface Tension • cohesion of water molecules

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

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

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

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

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

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.

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

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

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

38. pH scale

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

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.