2. The Extraordinary Properties of Water

3. Warm-up Write the chemical formula for water. Draw a water molecule. Indicate its atoms and their charges.

4. The Water Molecule

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

6. Water is Polar oxygen atom has a very strong attraction (high affinity) for the electrons of the hydrogens.In each water molecule, the oxygen atom has a very strong attraction (high affinity) for the electrons of the hydrogens. oxygennegative.The oxygen end “acts” negative. hydrogenpositive.The hydrogen end “acts” positive. POLAR.This causes the water molecule to be POLAR. A polar molecule is one that has an unequal distribution of charge.A polar molecule is one that has an unequal distribution of charge.

7. Hydrogen Bonds Exist Between Water Molecules Formed between a highly electronegative atom of a polar molecule and a hydrogen of a different moleculeFormed between a highly electronegative atom of a polar molecule and a hydrogen of a different molecule One hydrogen bond is weak, but many hydrogen bonds are strong.One hydrogen bond is weak, but many hydrogen bonds are strong.

8. Interactions Between Water Molecules The negative oxygen side of one water molecule is attracted to the positive hydrogen side of another water molecule and forms a HYDROGEN BOND.

9. What are the Properties of Water?

10. Properties of Water CohesionCohesion

11. Properties of Water CohesionCohesion AdhesionAdhesion

12. Properties of Water CohesionCohesion AdhesionAdhesion High Specific HeatHigh Specific Heat

13. Properties of Water CohesionCohesion AdhesionAdhesion High Specific HeatHigh Specific Heat High Heat of VaporizationHigh Heat of Vaporization

14. Properties of Water CohesionCohesion AdhesionAdhesion High Specific HeatHigh Specific Heat High Heat of VaporizationHigh Heat of Vaporization Less Dense as a SolidLess Dense as a Solid

15. Properties of Water CohesionCohesion AdhesionAdhesion High Specific HeatHigh Specific Heat High Heat of VaporizationHigh Heat of Vaporization Less Dense as a SolidLess Dense as a Solid Universal SolventUniversal Solvent

16. Universal Solvent Polarity makes Water a good solvent Solvent = a substance in which another substance is dissolved Solute = the substance dissolved in a solvent Solution = when a solvent and solute are combined solvents dissolve solutes creating solutions

17. Solution Ionic compounds disperse as ions in water (Salt = Na+ and Cl-)Ionic compounds disperse as ions in water (Salt = Na+ and Cl-) Water molecules then attach to the ions dissolved in the solution.Water molecules then attach to the ions dissolved in the solution.

18. What dissolves in water? Hydrophilic –substances that have an attraction to H 2 O –polar or non-polar? Honors Biology

19. What doesn’t dissolve in water? Hydrophobic –substances that don’t have an attraction to H 2 O –polar or non-polar? fat (triglycerol) Oh, look hydrocarbons! Honors Biology

20. Cohesion Attraction between molecules of the same substance (why water is attracted to itself).Attraction between molecules 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 water.Produces a surface film on water that allows insects to walk on the surface of water.

21. Cohesion … Helps insects walk across water

22. 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. Capillary action-water molecules will “tow” each other along when in a thin glass tube.Capillary action-water molecules will “tow” each other along when in a thin glass tube. Example: transpiration - process in which water evaporates from plant leaves. Water is simultaneously drawn up through roots from surrounding soil and delivered to rest of plant through veins.Example: transpiration - process in which water evaporates from plant leaves. Water is simultaneously drawn up through roots from surrounding soil and delivered to rest of plant through veins.

23. Adhesion Causes Capillary Action Gives water the ability to “climb” structures

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

25. High Specific Heat Amount of heat needed to raise or lower 1g of a substance 1° C. Amount of heat needed to raise or lower 1g of a substance 1° C. 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.

26. High Heat of Vaporization Amount of energy to convert 1g of a substance from a liquid to a gasAmount of energy to convert 1g of a substance from a liquid to a gas In order for water to evaporate, hydrogen bonds must be broken.In order for water to evaporate, hydrogen bonds must be broken. As water evaporates, it removes a lot of heat with it.As water evaporates, it removes a lot of heat with it.

27. High Heat of Vaporization 540 cal/g.Water's heat of vaporization is 540 cal/g. In order for water to evaporate, each gram must GAIN 540 calories (temperature doesn’t change --- 100 o C).In order for water to evaporate, each gram must GAIN 540 calories (temperature doesn’t change --- 100 o C). As water evaporates, it removes a lot of heat with it (cooling effect).As water evaporates, it removes a lot of heat with it (cooling effect).

28. Water vaporWater vapor forms a kind of global ‘‘blanket” which helps to keep the earth warm. Heat radiates from the sun.Heat radiates from the sun. The surface of the earth is warmed as heat is Absorbed by water vapor in the atmosphere vapor in the atmosphere.

29. Water is Less Dense in Solid form. 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 due to their H-bonds.

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

31. Water is Less Dense as a Solid WaterIce

32. Homeostasis The ability to maintain a steady state despite changing conditions.The ability to maintain a steady state despite changing conditions. Water is important to this process because:Water is important to this process because: a. It acts as a good insulator b. Resists temperature change c. Universal solvent d. Coolant e. Ice protects against temperature extremes (insulates frozen lakes)

33. http://www.brainpop.com/science/e arthsystem/water/ http://www.bozemanscience.com/w ater-life

34. Properties of Water At sea level, pure water boils at 100 °C and freezes at 0 °C.At sea level, pure water boils at 100 °C and freezes at 0 °C. The boiling temperature of water decreases at higher elevations (lower atmospheric pressure).The boiling temperature of water decreases at higher elevations (lower atmospheric pressure). For this reason, an egg will take longer to boil at higher altitudes.For this reason, an egg will take longer to boil at higher altitudes.