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Chemistry Topics for Us

Chemistry Topics for Us. Plant + animal chemical defenses Atomic structures: Protons, Neutrons, Electrons Special properties of water pH: acids + bases Light + Energy Organic Chemistry: Carbohydrates, Proteins, Lipids + Nucleic Acids.

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Chemistry Topics for Us

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  1. Chemistry Topics for Us • Plant + animal chemical defenses • Atomic structures: Protons, Neutrons, Electrons • Special properties of water • pH: acids + bases • Light + Energy • Organic Chemistry: Carbohydrates, Proteins, Lipids + Nucleic Acids

  2. Milkweed contains cardiac glycosides that are poisonous to humans and livestock, as well as alkaloids.  The glycoside in milkweed is also a chemical defense for monarch butterflies. Caterpillars eat the milkweed plant and store the poisons and make the caterpillar's flesh distasteful to most predators. 

  3. Captive bluejays fed monarchs with cardenolides throw up after eating the monarchs.

  4. Plants containing cardiac steroids have been used as poisons and heart drugs at least since 1500 B.C.

  5. Periodic Table of the Elements

  6. ELEMENT = Its all about the Protons! = a substance that can’t be chemically changed into another substance H=hydrogen, C= carbon, O=oxygen,Au=gold ELEMENT = # of Protons in an atom H = 1, He = 2, C = 6, O = 8, Au = 79 ELEMENT = Atomic # = # of Protons So, if you: Change # Protons in an atom you Change the Element !

  7. The nucleus is surrounded by electrons, which orbit so fast they form “clouds” around the nucleus • An atom has protons and neutrons located in a central nucleus 2 Protons Nucleus 2 Neutrons 2 Electrons Figure 2.4A A. Helium atom

  8. Common Elements in Organic Molecules

  9. electron transfer SODIUM ATOM 11 p+ 11 e- CHLORINE ATOM 17 p+ 17 e- SODIUM ION 11 p+ 10 e- CHLORINE ION 17 p+ 18 e-

  10. The Amazing Water Molecule • Life began in water • All living things depend on water • Water is a simple molecule, but without it, Earth may not be inhabitable …but why?

  11. Water Molecule = Atoms sharing electrons

  12. So, the oxygen end of the molecule slightly negatively charged • The hydrogen end of the molecule is slightly positively charged • Water becomes a “POLAR” molecule Electrons drawn to this side • In a water molecule, oxygen’s 8P has a stronger pull on the shared electrons than hydrogen’s 1P (–) (–) 8 protons O H H 1 proton 1 proton (+) (+) Figure 2.9

  13. Water’s polarity leads to hydrogen bonding and unusual properties \ • water molecules are attracted to the oppositely charged regions on nearby molecules • This attraction forms weak bonds called hydrogen bonds

  14. H-bonds =Water is a versatile solvent • Reason why things dissolve in water • Note: only polar molecules dissolve in water • What substances don’t dissolve in water?

  15. TRANSPIRATION IN PLANTS Evaporation “pulls” water into the roots molecule by molecule Adhesion + cohesion Molecule by molecule water enters the roots

  16. Water and it’s Hydrogen Bonds • Xylem cells allow plants to draw water from soil without energy (adhesion + cohesion) Xylem Plant Vascular Cells

  17. High Specific Heat • Reason why rivers, lakes and oceans stay relatively cool • it takes a lot of energy to warm up water • energy is absorbed by hydrogen bonds • This, in turn, keeps our planet from overheating quickly.

  18. Evaporative Cooling • Reason why sweating cools you off so effectively – • High heat of vaporization (takes lots of energy to evaporate water)

  19. Ice is less dense water • So, ice floats and so fish can survive winter under lake ice.

  20. Water: A Unique Compound • 60 - 70 % of the weight of living organisms • liquid where all of life's chemical reactions occur • Good electrical conductor • Highest surface tension of any common, natural liquid = adhesion + cohesion properties • Expands when it crystallizes, unlike most substances (ice has greater volume than water) • High specific heat (water holds a lot of heat energy) • High heat of vaporization (takes lots of energy to evaporate water)

  21. Acids and Bases • Acids are compounds that readily release hydrogen ions (H+) in water. • Bases are substances that readily take up hydrogen ions (H+) and release hydroxide ions (OH-) in solution. • pH scale = Strength measured by concentration of H+ (protons) in water • 0-14 scale

  22. The pH Scale

  23. The chemistry of life is sensitive to acidic and basic conditions • A compound that releases H+ ions in solution is an acid, and one that accepts H+ ions in solution is a base • Acidity is measured on the pH scale: • 0-7 is acidic • 8-14 is basic • Pure water and solutions that are neither basic nor acidic are neutral, with a pH of 7

  24. As carbon dioxide levels go up, pH levels go down. Acidity depends on the presence of hydrogen ions (the H in pH) and more hydrogen ions mean, a lower pH. Expose oceans to more CO2 it will produce carbonic acid, lowering pH on a planetary scale.  Ocean pH + CO2

  25. Acid Rain • When water vapor in the atmosphere mixes with acidic air borne particles (NO2 or SO2) it can kill leaves, trees, fish, etc. H2O + SO2 H2SO4 (sulfuric acid) H2O + NOx H2NOx (nitric acid)

  26. The Electromagnetic Spectrum The wavelengths of visible light drive photosynthesis.

  27. Photosynthesis=CO2 + H20 C6H12O6 + H2O

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