1. Water
The elixir of life!!

2. Water : Common Information...
It is colorless, odorless, and tasteless
It is the simplest molecule
It is made from the 2 most common elements in the universe H O

3. But Very Unique!!! It is the most studied material on earth.
Living things cannot survive without it
It is used for many purposes (can you name some?)
Our bodies are about 2/3 water.

4. THE WATER MOLECULE
1 Oxygen atom
Bonded
to 2 Hydrogen atoms

5. Sharing electrons…
Water molecules have positive and negative atoms. The water molecule is neutral because, opposites attract, so a positively charged atom (hydrogens) will pair up with a negative atom (oxygen).
The electrons spend more time around the Oxygen atom.

6. If oxygen has the electrons around it more often, it will have a slightly negative charge.
This means that the hydrogen atoms will have a slightly positive charge.

7. We call this uneven sharing…
Polar molecule – has positive and negative parts (unequal sharing of electrons)
(+) charge ----
---- (-) charge
(+) charge -----

9. Simply put…
Polar Molecule: A molecule with an uneven charge

10. POLAR VS NON POLAR Polar = Hydrophilic (water loving)
Non Polar = Hydrophobic
(water fearing)

11. WATER: THE UNIVERSAL SOLVENT
Almost everything will dissolve in water!!!!
Solvent - something that dissolves another material
Solute - the material that dissolves
SOLVENT + SOLUTE = SOLUTION

12. WATER: THE UNIVERSAL SOLVENT
BEFORE ADDING WATER
AFTER ADDING WATER

13. WATER: THE UNIVERSAL SOLVENT
Because water is polar, anything else that has areas of charge will be able to dissolve in it.

14. WATER: THE UNIVERSAL SOLVENT
Why might this property be important to living things?
It allows most substances to dissolve in water- our blood is mostly water, so things like sugars and gasses can dissolve in it.

15. More about water
When many water molecules are placed in the same area, the + and -- sides will attract.
This forms bonds between neighboring molecules called hydrogen bonds.

17. THIS CAUSES WATER MOLECULES TO STICK TO ONE ANOTHER!!!!
HYDROGEN BONDING
Hydrogen bonding – when the positive ends of one molecule are attracted to the negative end of another molecule
THIS CAUSES WATER MOLECULES TO STICK TO ONE ANOTHER!!!!

18. Hydrogen bonds cause water to “stick” to itself.
This property is called cohesion.

19. This force also causes something called adhesion molecules are attracted to others and they try to squish together in the smallest possible space.

20. In other words… Water is sticky!!
Water can stick to other water molecules = cohesion
Water can stick to other molecules = adhesion

21. CAPILLARY ACTION
Capillary Action – the tendency of a liquid substance to move a long a solid substance due to adhesion (to stick to something)

22. Capillary Action This helps
Trees and tall plants get the water they need
Blood flow back up the veins in your legs

23. SURFACE TENSION
Water molecules under the surface are stuck to each other
Water molecules at the surface line don’t have anyone to “cling” to so they turn inward
This causes the top layer of molecules to act like a thin membrane

24. Surface Tension pictures

25. Why a belly flop hurts!
You’re breaking the Surface Tension with your Body!!

26. More about water…
Another property of water is the fact that as it freezes, it expands.
This is important because ice floats.

27. Because of hydrogen bonds, water is very effective at maintaining a stable temperature

28. This helps maintain living systems because living things are made of about 70% water.
Distribution of Weight in the Human Body

29. Water Fact and Fiction Water has some very interesting properties.
See if you can separate the fact from the fiction!!
Take out a sheet of notebook paper
Number your paper from 1 – 10
Write down if you think the following statements about water are true or false

30. 1. Water contracts (gets smaller) when it freezes.
2. Water has high surface tension.
3. Condensation is water coming out of the air.
4. More things can be dissolved in acid than in water.
5. Rainwater is the purest form of water.

31. 7. Sea water is slightly more basic than fresh water.
6. If you evaporate an 8 inch tall glass of water from the salt lake (about 20% salinity) you will end up with about 1 inch of salt.
7. Sea water is slightly more basic than fresh water.
8. Tap water is slightly more acidic than distilled water.
9. Raindrops are tear shaped.
10. Water boils more quickly in Denver, CO than here in Baltimore, MD.

32. 1. Water contracts (gets smaller) when it freezes.
FALSE
2. Water has high surface tension.
TRUE
3. Condensation is water coming out of the air.
4. More things can be dissolved in acid than in water.
5. Rainwater is the purest form of water.

33. 7. Sea water is slightly more basic than fresh water.
6. If you evaporate an 8 inch tall glass of water from the salt lake (about 20% salinity) you will end up with about 1 inch of salt.
TRUE
7. Sea water is slightly more basic than fresh water.
8. Tap water is slightly more acidic than distilled water.
9. Raindrops are tear shaped.
FALSE
10. Water boils more quickly in Denver, CO than here in Baltimore, MD.