1. Properties of Water
Discuss the special properties of water that contribute to Earth's suitability as an environment for life: cohesive behavior, ability to moderate temperature, expansion upon freezing, and versatility as a solvent.

2. Properties of Water
Objective: Explain how the polarity of a water molecule contributes to its unique properties.
Essential question: How are the unique properties of water contributed to polarity and hydrogen bonding?

3. Investigate Fill a clean, soap-free bowl with water.
See if you can get 3 paper clips to float on top of the water. Keep the fourth paperclip out of the cup.
What happens if you just drop it? How did you get them to float?

4. What is the Structure of a Water Molecule?
1. Water is composed of 1 oxygen atom and 2 hydrogen atoms.
2. The oxygen has a negative charge and the hydrogen has a positive charge.

5. Draw this in your notes!
The hydrogen atoms are always in the “ear” position due to the sharing of electron
A water droplet is made up of
1.674 x 10 ^21 molecules

6. A B D C Practice Which diagram of a water molecule is correct?
Choose the answer AND explain why. A B
C. Ears and correctly labeled charges D C

7. Why is water polar? Polarity- The state of having 2 opposite ends
water is polar Since the oxygen atom is slightly negative and the 2 hydrogen atoms are slightly positive
O and H are bonded to form one water molecule with slightly (+) and (-) ends (polar covalent bonds)
What else has a positive and negative end?
When do we use the word polar?
**** talk about polarity before the structure of water molecules!!!!

8. What is Hydrogen Bonding?
The bond between the oxygen (O) and Hydrogen (H) atoms of two different water molecules and other polar molecules
The positive H is attracted to the negative O of other water molecules.
Hydrogen bonds are weak allowing water to move and reform bonds often

9. What are the properties of water?
Key Points
1. The structure of a water molecule is reason for water’s polarity and ability to form hydrogen bonds. 2. Polarity and Hydrogen Bonding allow for the properties of water to exist
What are the properties of water?

10. Four Properties of Water (That no other substance has)
Cohesive Behavior (cohesion & Adhesion)
Ability to moderate temperature
Expanding upon freezing (density)
Universal solvent

11. 1. Cohesive Behavior: Cohesion
Water is highly cohesive
Co= together
“hesion”= to stick
Cohesion is the attraction of water molecules to stick together
Cohesion allows for water to have surface tension
Co-ed, co-worker, cooperate…
Ex. Water striders don’t break the high surface tension of water, allowing them to stay on the surface

12. 1. Cohesive Behavior: Adhesion
Adhesion is the attraction of water molecules to another substance.
Ad=another
Adhesion allows for capillary action, which allows water to move against the force of gravity
How does water get to the top of the tree if I only watered the soil?

13. Practice with Adhesion & Cohesion (whiteboard)
What property of water does this each picture represent? 1. 2. 3.

14. 2. Ability to Moderate Temperature
It takes a lot of energy to change the temperature of water.
High heat capacity
In the picture, what is going to heat up and cool down faster? Land or water?

15. Water absorbs LARGE amounts of energy before the Hydrogen bonds break
Water’s ability to
Moderate temperature
Water absorbs LARGE amounts of energy before the Hydrogen bonds break O H O H O H
Energy
Energy
Energy
Energy
Energy
Energy

16. Water’s ability to
Moderate temperature
Soil
Water

17. 3. Expanding Upon freezing
Density is how tightly packed the atoms in a substance are
1. Objects with greater/more density will sink.
2. Objects with smaller/less density will float.
As water freezes, the molecules spread out, leaving more space between them and decreasing the density. This is why ice floats!

18. If the formula for water is H2O, then what is the Formula for ice?
H2o cubed!

19. 4. Universal Solvent Solvents dissolve other substances (solute)
Water is a universal solvent because water can dissolve other polar substances
Water molecules act like magnets that pull apart other substances because of the positive and negative ends

20. Solute Water as a Solvent Dissolves almost everything!

21. Universal solvent
Solvent: usually a liquid; dissolves the other substance
Solute: usually a solid; what is being dissolved
Solution: a homogeneous mixture; formed when one
substance dissolves in another
We know that water dissolves sugar, but that it doesn’t dissolve oil. What can we conclude about the sugar and oil molecules??
Since water is polar and it dissolves sugar, the sugar molecule must be polar.
Since water doesn’t dissolve oil, the oil molecule must be nonpolar

22. Why does water have these unique properties?
The Water molecules’ Structure!!!

23. Revisit the floating paperclip
What property is causing them to float?
What is allowing for that property to exist?
Predict what will happen if you add soap to your cup
Try floating a paper clip now that the water has soap in it. What happens?

24. Building Water Molecules
Working with your table partner, read through the article and follow instructions to build water molecules.
C- level 2
H- ask three before me
A- build water molecules and then answer the discussion questions on the LEFT side of your notebook (do not write on pink sheet, it’s a class set!)
M- remain seated in your assigned seat
P- work with your partner to complete activity (17 min)
Success!

25. Exit Ticket Clear your desk of everything but a writing utensil
Answer essential question

26. Properties of Water: day 2
Discuss the special properties of water that contribute to Earth's suitability as an environment for life: cohesive behavior, ability to moderate temperature, expansion upon freezing, and versatility as a solvent.

27. Properties of water day 2
Objective: List and describe how each of the four properties of water make it essential for life on Earth.
Essential Question: How do the unique properties of water allow life to exist on Earth?

28. Remember….
All properties of water are caused by Polarity and Hydrogen Bonding
Hydrogen Bonding- the positive hydrogen of one molecules attracts to the negative oxygen of another water molecule
Polarity- positive (+) hydrogen and negative (-) oxygen

29. Why is water’s cohesive behavior important to life?
COHESION: water molecules stick together
Surface tension causes water to clump in drops
Allows very light insects to walk on water
ADHESION: water molecules stick to another substance
Capillary action–allows water to move through plant roots and stems and the smallest blood vessels in your body
as one molecule moves up the tree root or through the capillary, it 'pulls' the others with it

30. Why does water density impact life? (expand when freezing)
solid ice is LESS dense than liquid water due to expanding when freezing
Floating ice will keep the water underneath warm
This allows fish and other organisms to survive in the winter.
What would happen to the pond life if solid ice was more dense?

31. Why is water’s ability to moderate temp important to life?
It takes a lot of energy to heat water
Water’s ability to moderate temperature can protect an ecosystem from extreme temperature differences
Maintain Homeostasis

32. Why is water’s solubility important to life?
 Works like a magnet to pull apart other polar substances
Wherever water goes, it carries dissolved chemicals, minerals, and nutrients that are used to support living things

33. Lab and Task cards
The class will be split in half, while half the class is working in groups on the lab at the lab stations in the back, the others will be working on the property of water task cards. After 28 min we will switch.
C- level 2 (group should hear you)
H- raise a silent hand
A- rotating through the lab or working on the P.o.W. task cards
M- lab: remain at lab table and rotate on Ms Beck’s call
task cards: remain seated at assigned table
P: work with your group/partner to complete the lab and task cards.
Success