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Unit 2:Chemistry of Life

Unit 2:Chemistry of Life . Atoms, Ions and Molecules Properties of Water Acids and Bases Organic Molecules Chemical Reactions Enzymes. Atoms, Ions and Molecules. This topic looks at some Chemistry basics that are essential for understanding life.

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Unit 2:Chemistry of Life

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  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.

  5. “CHONPS” + 4

  6. “CHONPS”

  7. 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.

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

  9. 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

  10. 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

  11. Polar Covalent Bonds

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

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

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

  15. 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.

  16. States of Matter

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

  18. Surface Tension • cohesion of water molecules

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

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

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

  22. 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

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

  24. 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.

  25. 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

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

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

  28. pH scale

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

  30. 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.

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