1. Bellwork: 10/1 Put phone up  Week 10/1-10/5
Turn in chemical bonding worksheet
List some properties of water that you already know.
Did you have a good weekend?

2. Objective
Students will learn about how biochemistry is an important branch of biology
Determine what chemical properties of water make it unique to life
Determine what key properties of water makes it biologically significant

3. Today:
Tests back
Properties of Water Notes

4. This Week: Monday: H2O Notes
Tuesday: Lab Notebook, Pre-Lab, Water POGIL
Wednesday: H2O Lab
Thursday: H2O Lab, pH Notes
Friday: Internet Safety pt. I & II

5. Materials
Unit 2 Book

6. Homework Google Classroom Quiz Read pages 4—43 & answer ?s on GC
Due 11:59pm
Read pages 4—43 & answer ?s on GC
11:59pm tonight

7. Unit 2: Biochemistry

8. Part III: Properties of Water

9. Water Molecules are Polar
Why?
Oxygen loves electrons
Oxygen attracts Hydrogen’s Electrons
Makes Oxygen partially negative
Makes Hydrogen partially positive
Are these bonds covalent or Ionic? Why?

10. Chemical Bonds Covalent bonds-within water molecule
Hydrogen bonds-between water molecules
Covalent Bond
Hydrogen Bond

11. Activity
On your note guide, draw three water molecules. Indicate the Hydrogen bonds associated with these water molecules with dotted lines.
Be ready to share 

12. Unique Properties Water has unique properties because… It is polar
Forms Hydrogen bonds

13. The Five Properties of Water

14. 1) Excellent Solvent Solvent – dissolving agent of a solution
Solute – substance dissolved in the solvent
Hydrophilic (polar) – likes water, dissolves
Ex. Salt, table sugar
Hydrophobic (non-polar) – dislikes water, doesn’t dissolve
Ex. oil
Solution = solvent (liquid) + solute (may be solid, liq or gas)

15. Water as a Solvent
Water dissolves solutes (ex. table salt, sugar) by forming a hydration shell around the solute

16. Biological Significance
Allows solutes to be dissolved in our blood and transported throughout our body
Blood is 90% water

17. Is ice more or less dense than liquid water?

18. 2) Ice Floats Ice is less dense than liquid water
Density= # molecules per volume
Fewer molecules per volume in ice...floats!
Arsenic, bismuth, galium, germanium, silicon all have more dense liquids

19. When Water Turns to Ice…
A crystal lattice forms
Hydrogen bonds hold the water molecules in place
Molecules in ice are farther apart than in water
Fewer molecules per volume = less dense

20. Biological Significance
Only the surface of lakes and rivers freeze
Keeps the water below warmer
Stays liquid water
Prevents aquatic organisms from freezing

21. 3) Moderates Temperature
Water has a high specific heat because of hydrogen bonds.
Specific heat is the amount of heat absorbed or released by one gram of substance that causes the temperature to change by 1oC
Liquid  gas = absorbs heat because breaking hydrogen bonds
Liquid  solid = release heat because forms hydrogen bonds
Highest specific heat of any liquid – 1 calorie…H bonds are strong and hard to break
Takes water 5 times longer than sand to cool or heat

22. 3) Moderates Temperature
Water can absorb heat without changing temperature
because of hydrogen bonds.
Heat is used to break the hydrogen bonds rather than raising temperature
Heat used to break hydrogen bonds when
Ice melts to liquid water
Liquid water changes to water vapor (a gas)
Because of how strong those hydrogen bonds are

23. Biological Significance
Earth has more moderate temperatures because of the lakes, rivers and oceans
Favorable temperatures for survival of living organisms

24. Biological Significance
Homeostasis of body temperature
Evaporative cooling (sweating)
sweat absorbs heat from your body
causing the sweat to evaporate
You feel cool and don’t overheat

25. 4) Cohesion
Attraction between water molecules because of water bonding
Causes water to form droplets

26. Biological Significance
Creates strong Surface Tension
Insects can walk on water without sinking

27. 5) Adhesion
Attraction to unlike substances – like cellulose in the paper straw

28. Biological Significance
Capillary Action
Pulls water up a tube
Contributes to movement of water up tall trees

29. Answer the ?s in your Note Guide
Properties of Water Questions
Explain why water is polar.
How does its polarity contribute to its ability to form hydrogen bonds?
Describe the five properties of water and explain their biological significance.