1. Water as the basis of life

2. Materials: worksheet
Catalyst: How does the refrigerator keep foods from spoiling?
Hint: how are the enzymes affected?

3. Materials: worksheet Catalyst:
What is the difference between cohesion and adhesion?
What does it mean to say that a molecule is polar?

4. Elite Eight Trait Check-Up
Respect the Threshold
Everyone on time?
Silent for First Five?
Be Prepared (2 min)
Seated
Have materials
Working on catalyst

5. Class Motto
If there is a problem, We look for a solution. If there is a better way, We find it. If we need help, We ask. If a teammate needs help, We give.

6. announcements Science and Engineering Expo worksheet due Thurs/Fri
Test corrections must be made by next Friday (before Thanksgiving break)
This is the best way to bring up your grade!

7. What is the chemical formula for water
What is the chemical formula for water? Draw the structure of water (give it your best guess if you don't know)

8. Where is water? 3/4 of Earth’s atmosphere is made of water
Life on earth began in water and evolved from this supportive life source
Cells are 70% water

9. Properties of Water
Polarity
Cohesion
Causes surface tension
Adhesion

10. Structure of Water O H H Water looks like this:
Partial NEGATIVE (-) charge O H H
Partial POSITIVE (+) charge
Partial POSITIVE (+) charge

11. POLARITY It has a positive end and a negative end.
This is called polar (like a magnet).
It dissolves other polar molecules.
Water’s polarity helps it dissolve many substances.

12. Why is Oxygen more negative?
Electrons have a negative charge
Oxygen attracts more than its fair share of electrons
More electrons = more negative charge

13. Polarity

14. Polarity Example
Will salt dissolve in a beaker of water? Why or why not??
Chemical formula for salt is NaCl.
The Na has a partial positive charge
The Cl has a partial negative charge
It WILL dissolve because it is POLAR!

15. THINK!
Water is often called the "universal solvent" because many common substances dissolve in water. Why do so many substances dissolve in water?
A. There is an abundance of water on Earth.
B. The water molecule only contains two elements.
C. The water molecule has a polar structure.
D. Hydrogen and oxygen are very reactive when they are combined.

16. THINK!
Water is often called the "universal solvent" because many common substances dissolve in water. Why do so many substances dissolve in water?
A. There is an abundance of water on Earth.
B. The water molecule only contains two elements.
C. The water molecule has a polar structure.
D. Hydrogen and oxygen are very reactive when they are combined.

17. Balloon Demonstration
What happens to the balloon when we rub it on someone’s hair?
What happens to the stream of water when we put the balloon next to it?
Why does this happen? Describe using a property of water.

18. Cohesion Attraction between LIKE particles
Example: water is attracted to water
Hydrogen bonds hold water molecules closely together
Tight links make water more structured than most liquids

19. Example: Cohesion in Plants
Helps transport of water and dissolved nutrients in plants
(as water evaporates, H-bonds pull lower molecules up toward leaves)

20. Cohesion in plants

21. Surface tension A measure of the strength of the water’s surface
Cohesion creates a “film” on top of water
Responsible for insects “walking on water”

22. Jesus Lizard Video

23. Penny Experiment
Draw a picture of what your penny looked like right before the water dome broke.
What property of water makes the drops behave like they do? 
What does a high surface tension do to the number of liquid molecules that can stay together?
Which type of water holds more drops on the penny: regular or soapy?________________________________
Why? What property of water is affected by soap?

24. Adhesion Attraction between two UNLIKE particles
**Graduated Cylinder demo!

25. PANTHER PASS

26. Panther Pass What makes a water molecule polar?
Water has the ability to be frozen.
The pH of water varies with temperature.
A water molecule has a slight charge on each end.
A water molecule is made up of 3 atoms.

27. 2. Define Adhesion.
3. Define Cohesion.
4. What property of water allows water to dissolve many other substances?
5. What property of water allows insects to walk across the surface?