1 / 40

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.

nyx
Télécharger la présentation

Unit 2:Chemistry of Life

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  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 • result is a charge separation in the molecule, where one part of the molecule has a partial negative charge and one part has a partial positive charge

  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 • other molecules that have polar covalent bonds are peptide bonds and amines • 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 • formed when a charged part of a molecule having polar covalent bonds forms an electrostatic interaction with a substance of opposite charge • molecules that have nonpolar covalent bonds do not form hydrogen bonds • classified as weak bonds because they are easily and rapidly formed and broken under normal biological conditions • under the right environmental conditions, any compound that has polar covalent bonds can form hydrogen bonds

  13. Hydrogen Bonds • important in biological systems • explains many of the properties of water • used to stabilize and determine the structure of large macromolecules like proteins and nucleic acids • involved in the mechanism of enzyme catalysis

  14. What characteristic of an atom gives it its chemical properties? • the number of protons • the number of neutrons • the number of electrons • the number of electrons in its outer orbital

  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 – wateris attracted to other water molecules • Adhesion – wateris attracted to other materials • oxygen end of water has a negative charge • hydrogen end has a positive charge • hydrogens of one water molecule are attracted to oxygen of another water molecule • this attractive force is what gives water its cohesive and adhesive properties

  18. Surface Tension • cohesion of water molecules at the surface of a body of water • all the water molecules on the surface of a quantity of water (a bead, cup, pond, etc.) are 'holding' each other together, creating surface tension

  19. Cohesion & Adhesion • Surface tension allows water striders to 'skate' across the top of a pond. • Many objects are heavier than water, but because of surface tension, the water is able to hold up the metal. • Surface tension is not the force that keeps boats floating.

  20. Capillary Attraction • related to adhesive properties of water • click here for demonstration • water 'climbs' up the straw as the water molecules are attracted to the straw molecules • when one water molecule moves closer to the straw molecules the other water molecules (which are cohesively attracted to that water molecule) also move up into the straw.

  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 • Baking soda, Alka-seltzer, milk of magnesia • Antacids • OH ions bind with excess H+ ions, neutralizing the acid • Household cleaners

  27. Acids & Bases • Acidity of a liquid is measured as its concentration of hydrogen ions • pH scale expresses this concentration in logarithmic units • very acidic = pH 0 • neutral value = pH 7 • very alkaline (basic) = pH 14

  28. pH scale

  29. Organic Compounds • Substances that contain carbon • Carbon occurs in almost every chemical compound found in living things • Four main types of organic compounds in living things: • carbohydrates • proteins • lipids • nucleic acids

  30. Organic Compounds • Combination of carbon and almost any other element • Unique atomic structure allows a carbon atom to link up with as many as four other atoms of another • Also links up with other carbon atoms to form long, stable chains, variety of combinations carbon can form with other elements is almost limitless • FYI…scientists have already identified more than ten million organic compounds.

More Related