1. The Extraordinary Properties of Water

2. Water threeA water molecule (H 2 O), is made up of three atoms --- one oxygen and two hydrogen. H H O

3. Water is Polar oxygennegativeThe oxygen end “acts” negative hydrogenpositiveThe hydrogen end “acts” positive POLARCauses the water to be POLAR neutral Zero Net ChargeHowever, Water is neutral (equal number of e- and p+) --- Zero Net Charge

4. Hydrogen Bonds Exist Between Water Molecules One hydrogen bond is weak, but many hydrogen bonds are strongOne hydrogen bond is weak, but many hydrogen bonds are strong

5. Interaction Between Water Molecules Negative Oxygen end of one water molecule is attracted to the Positive Hydrogen end of another water molecule to form a HYDROGEN BOND

6. What are the Properties of Water?

7. Properties of Water CohesionCohesion

8. Properties of Water CohesionCohesion AdhesionAdhesion

9. Properties of Water CohesionCohesion AdhesionAdhesion Water absorbs/ retains heatWater absorbs/ retains heat

10. Properties of Water CohesionCohesion AdhesionAdhesion Water absorbs/ retains heatWater absorbs/ retains heat Less Dense as a SolidLess Dense as a Solid

11. 1. Cohesion Attraction between particles of the same substance (why water is attracted to itself)Attraction between particles of the same substance ( why water is attracted to itself) Results in Surface tension (a measure of the strength of water’s surface)Results in Surface tension (a measure of the strength of water’s surface) Produces a surface film on water that allows insects to walk on the surface of waterProduces a surface film on water that allows insects to walk on the surface of water

12. Cohesion … Helps insects walk across water

13. 2. Adhesion Attraction between two different substances.Attraction between two different substances. Water will make hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton.Water will make hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton. This will allow water to “climb” materialsThis will allow water to “climb” materials Example: transpiration process which plants and trees remove water from the soil, and paper towels soak up water.Example: transpiration process which plants and trees remove water from the soil, and paper towels soak up water.

14. Adhesion Causes Capillary Action Which gives water the ability to “climb” structures

15. Adhesion Also Causes Water to … Form spheres & hold onto plant leaves Attach to a silken spider web

16. Water absorbs/ retains heat Water resists temperature change, both for heating and cooling.Water resists temperature change, both for heating and cooling. Water can absorb or release large amounts of heat energy with little change in actual temperature.Water can absorb or release large amounts of heat energy with little change in actual temperature.

17. Water is Less Dense as a Solid Ice is less dense Ice is less dense as a solid than as a liquid (ice floats) hydrogen bonds constantly being broken and reformed. Liquid water has hydrogen bonds that are constantly being broken and reformed. Frozen water crystal-like lattice Frozen water forms a crystal-like lattice whereby molecules are set at fixed distances.

18. Water is Less Dense as a Solid Which is ice and which is water?Which is ice and which is water?

19. Water is Less Dense as a Solid WaterIce

20. Homeostasis Ability to maintain a steady state despite changing conditionsAbility to maintain a steady state despite changing conditions Water is important to this process because:Water is important to this process because: a. Makes a good insulator b. Resists temperature change c. Universal solvent d. Coolant e. Ice protects against temperature extremes (insulates frozen lakes)

21. Solutions & Suspensions Water is usually part of a mixture.Water is usually part of a mixture. There are two types of mixtures:There are two types of mixtures: –Solutions –Suspensions

22. Solution Ionic compounds disperse as ions in waterIonic compounds disperse as ions in water Evenly distributedEvenly distributed SOLUTESOLUTE –Substance that is being dissolved SOLVENTSOLVENT –Substance into which the solute dissolves

23. Solution

24. Suspensions don’t dissolve but separateSubstances that don’t dissolve but separate into tiny pieces. Water keeps the pieces suspendedWater keeps the pieces suspended so they don’t settle out.

25. Acids, Bases and pH One water molecule in 550 million naturally dissociates into a Hydrogen Ion (H+) and a Hydroxide Ion (OH-) Hydrogen Ion Hydroxide Ion Acid Base Acid Base H 2 O  H + + OH -

26. The pH Scale concentration of H + ionsIndicates the concentration of H + ions 0 – 14Ranges from 0 – 14 7 is neutralpH of 7 is neutral 0 up to 7 is acidpH 0 up to 7 is acid … H + above 7 – 14 is bpH above 7 – 14 is basic… OH - 10XEach pH unit represents a factor of 10X change in concentration pH 3 is 10 x 10 x 10 (1000) stronger than a pH of 6pH 3 is 10 x 10 x 10 (1000) stronger than a pH of 6

27. Acids Strong Acids have a pH of 1-3Strong Acids have a pH of 1-3 Produce lots of H + ionsProduce lots of H + ions

28. Bases Strong Bases 11 to 14Strong Bases have a pH of 11 to 14 lots of OH - ionsContain lots of OH - ions and fewer H+ ions

29. Buffers Weak acids or bases that react with strong acids or bases to prevent sharp, sudden changes in pH (neutralization).Weak acids or bases that react with strong acids or bases to prevent sharp, sudden changes in pH (neutralization). Produced naturally by the body to maintain homeostasisProduced naturally by the body to maintain homeostasis Weak Acid Weak Base