1. Water

2. WATER & its unique properties
make life possible

3. Water is ESSENTIAL to life.
Water & Living Things
Water is ESSENTIAL to life.
Living organisms are composed mostly of water.
Humans – 76%
Jellyfish – 90%
Dried beans – 50%

4. Structure of the Water Molecule
Is NOT 180 degrees
(H—O—H)
IS a little more than
a 90 degree angle.
Water is Polar – One end is positive, one end is negative.

5. What creates the HYDROGEN BOND?
Oxygen is slightly negative
Hydrogen is slightly positive
What creates the HYDROGEN BOND?
The +/- attraction between the H (+) of one water molecule and the O (-) of the adjacent water molecule.

6. Polarity & Hydrogen bonds http://videos. howstuffworks

7. Properties of Water “Universal Solvent” Freezes & Floats
Cohesion (Surface tension)
Adhesion (Capillary action)
High heat of vaporization
High heat of fusion

8. Solution A mixture of… Solute Solvent
A substance that is put INTO the solvent to dissolve.
Solvent
Substance that does dissolves the solute
Water - Universal Solvent

9. SUSPENSION
Ever hear…
Oil & water don’t mix???

10. Water is the Universal Solvent
BLOOD is 95% water.
Ions (NaCl) dissolve in blood (SOLUTION).
Water dissolves polar
(ionic) substances:
SALT (NaCl)
Water dissolves
non-polar molecules: O2
Helps fish survive
CO2
Helps algae survive

11. Water freezes & floats Liquid ICE
Ice is dense less than water
Ice has spaces between its water molecules
Imagine if ice didn’t float on top of a lake…
Ice acts as an insulator to allow the water below to remain a liquid.

12. Surface Tension Cohesion
Water molecules at the surface are not pulled from above.
Cohesion
This produces a “tension”.
The hydrogen bonds pull a water molecule in every direction by adjacent molecules.
What substance “broke” the
tension in the Water Lab?
The water strider bug relies on surface tension to survive.

13. Water has Capillary Action
COHESION – The attraction between water molecules
make them “stick” together.
ADHESION – The attraction between a
water molecule and another substance.
CAPILLARY – Any thin long tube.
CAPILLARY ACTION – DUE TO cohesion & adhesion Water acts like a magnet and pull itself up against gravity.
Living things have capillary tubes:
Animals - blood vessels
Plants – xylem/phloem
From - roots
To - leaves

14. Which substance has greater ADHESIVE properties?
COHESION: Water “sticks” to water
ADHESION: Water “sticks” to another substance
Red dyed water
Mercury
Which substance has greater ADHESIVE properties?

15. High heat of vaporization
Compared to other liquids it takes a lot of energy to evaporate water.
(Less evaporation leaves more water available for living things)

16. High heat of fusion
Large bodies of water change temperature more slowly than air does.
(Lakes/ponds stay warmer, longer for living things)