1. The Chemistry of Life Properties of Water 2.2

2. The Water Molecule Neutral Charge – ZERONeutral Charge – ZERO Have no charge Have an Equal number of p+ and e- Charges aren’t evenly distributed

3. The Water Molecule PolarityPolarity uneven distribution of electrons –A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms. (-) (+)

4. Hydrogen Bonds Polar water molecules act like magnets and attract each otherPolar water molecules act like magnets and attract each other Hydrogen BondsHydrogen Bonds –The attraction of the Hydrogen end (+) of one molecule for the Oxygen end (-) of another water molecule. They are bonds that form between molecules (CO 2, H 2 O)They are bonds that form between molecules (CO 2, H 2 O)

5. Hydrogen Bonds

6. Cohesion The attraction between molecules of the same substance (e.g. water). H 2 O attracting other H 2 O moleculesH 2 O attracting other H 2 O molecules Allows some insects and spiders to walk on water.

7. Basilisk Lizard and Water Strider http://www.youtube.com/watch?v=45yabrnryXk http://www.youtube.com/watch?v=RphuMEUY3 Oghttp://www.youtube.com/watch?v=RphuMEUY3 Og

8. Adhesion & Capillarity Adhesion - Attraction between H 2 O molecules and different moleculesAdhesion - Attraction between H 2 O molecules and different molecules How can you demonstrate this? Think!How can you demonstrate this? Think! Cohesion & adhesion produce Capillarity (upward movement against gravity of water through small tubes)Cohesion & adhesion produce Capillarity (upward movement against gravity of water through small tubes) Question: How do plants make use of Capillarity?

9. Capillary Action Helps plants draw up water against gravity: http://www.youtube.com/watch?v=y-h_qGhgtno http://www.youtube.com/watch?v=y-h_qGhgtno

10. Heat Capacity/Specific Heat H-bonds cause water to stick together—takes a lot of energy to make molecules move faster/heat up –Water resists temperature change—no wide fluctuations in temperature –Temperature moderation large bodies of water (environment) inside organisms

11. Solutions & Suspensions Water is usually part of a mixture.Water is usually part of a mixture. Because so many things dissolve in water, it is called the Universal SolventBecause so many things dissolve in water, it is called the Universal Solvent There are two types of mixtures:There are two types of mixtures: –Solutions—dissolved particles –Suspensions—undissolved particles

12. Properties of Solutions Ionic compounds disperse as ions in water (+ions & -ions spread out among polar water molecules)Ionic compounds disperse as ions in water (+ions & -ions spread out among polar water molecules) Solutions are Evenly distributed mixturesSolutions are Evenly distributed mixtures SOLUTE Substance that is being dissolved (ex. water)SOLUTE Substance that is being dissolved (ex. water) SOLVENT Dissolving Substance for the solute (ex. salt)SOLVENT Dissolving Substance for the solute (ex. salt)

13. Ionic Solutions Na+ ions will be attracted to WHAT END of the water molecule?

14. NaCl solution animation http://www.youtube.com/watch ?v=EBfGcTAJF4o

15. Suspensions Substances that don’t dissolve but separate into tiny pieces.Substances that don’t dissolve but separate into tiny pieces. Water keeps the pieces suspended so they don’t settle out.Water keeps the pieces suspended so they don’t settle out. Blood & Cytoplasm are suspensionsBlood & Cytoplasm are suspensions

16. Blood—solution AND suspension

17. pH Scale Draw and label from textbook. Song: http://www.youtube.com/watch?v=zTLiJE- j1-Ihttp://www.youtube.com/watch?v=zTLiJE- j1-I

18. Acids, Bases & pH 1 water molecule in 550 million naturally dissociates into a Hydrogen Ion and a Hydroxide Ion1 water molecule in 550 million naturally dissociates into a Hydrogen Ion and a Hydroxide Ion Hydrogen Ion Hydroxide Ion Acid Base Acid Base H 2 O  H + + OH -

19. The pH Scale Indicates the concentration of H + ions Ranges from 0 – 14 pH of 7 is neutral pH 0 up to 7  acid … H + pH above 7 to 14  base… OH - Each pH unit represents a factor of 10X change in concentration How much stronger is a pH3 than a pH of 5?

20. Acids Strong Acid = pH 1-3 High in H + ions Lower number of OH- ions

21. Bases Strong Base = pH 11 – 14 High in OH - ions Lower in number of H+ ions

22. Buffers Weak acids or bases that react with strong acids or basesWeak acids or bases that react with strong acids or bases Made by the bodyMade by the body Prevent sharp, sudden changes in pH (keep pH neutral)Prevent sharp, sudden changes in pH (keep pH neutral) Weak Acid Weak Base

23. Buffers cont. Human body: 6.5-7.5 Blood: 7.4 Buffers dissolved in organisms’ aqueous environment help maintain homeostasis.

24. Animations Hydrogen bonding: www.classzone.com

25. Assessment Draw 3 molecules of water. Show polarity and hydrogen bonding. Make sure to orient the molecules correctly. Complete the 2.2 assessment in your text. Go to www.classzone.com and practice—games or practice quizzes.www.classzone.com