1. Bonding Unit
Water Properties

2. Water Formula = H2O Molecular Mass = 18
State at Room Temperature = Liquid
Melting Point = 0 oC
Boiling Point = 100 oC
Less Dense as a solid

4. Intermolecular Forces
Creates Order
Hydrogen Bonding
In pure water, each water molecule may form hydrogen bonds with four other water molecules.

6. Hydrophobic –vs- Hydrophilic
Nonpolar molecules that repel the water molecules are said to be hydrophobic.
molecules forming ionic or a hydrogen bond with the water molecule are said to be hydrophilic.

7. Surfactants
Surfactants are compounds that lower the surface tension between two liquids or between a liquid and a solid.

9. States of Water

10. Universal Solvent
Water is capable of dissolving a variety of different substances, which is why it is such a good solvent.
water is called the "universal solvent" because it dissolves more substances than any other liquid.
This is important to every living thing on earth.

11. Importance to Living Organisms
Next to oxygen, water is essential for all living organisms on Earth.
It is a major component in cells, which make up all living organisms; therefore approximately 60% to 95% of living organisms are water.

12. Importance to Living Organisms
Water has many useful biological roles such as:
being a solvent
a coolant
an insulator
as support
a lubricant
a reagent.
Water is used
in chemical reactions
for transporting
providing a suitable environment

13. Surface Tension The tendency of liquids to keep a low surface area.
Liquids with stronger cohesion (intermolecular forces) tend to have higher surface tension.
Water has a very high surface tension.

14. Adhesion –vs- Cohesion
Adhesion is the attraction of molecules of one kind for molecules of a different kind.
it can be quite strong for water, especially with other molecules bearing positive or negative charges.
Cohesion refers to the attraction of molecules for other molecules of the same kind.
Water molecules have strong cohesive forces thanks to their ability to form hydrogen bonds with one another.

15. Capillary Action
Results from the adhesive force between the molecules of liquid and the side of the tube.
Adhesive forces are the attractive forces between two unlike molecules.

17. Specific Heat
The heat required to raise the temperature of the unit mass of a given substance one degree.

18. Water and Heat
Water absorbs or releases the most heat of the common substances when changing temperature.
That is why it takes a long time for a swimming pool to heat up or cool down.

19. Water and Heat
Water's high heat capacity is a property caused by hydrogen bonding among water molecules.
When heat is absorbed, hydrogen bonds are broken and water molecules can move freely.
When heat is released, the hydrogen bonds are formed and considerable amount of energy is released.

20. Phase Change
Evaporation (liquid to a gas) is endothermic (energy-absorbing) because intermolecular forces must be overcome.
You must add heat to boil water.
Condensation (gas to a liquid) is exothermic (energy-releasing)
You must cool water vapor to get it to turn into liquid water.

21. Phase Change

22. Ice
Ice floats because it is about 9% less dense than liquid water. In other words, ice takes up about 9% more space than water, so a liter of ice weighs less than a liter water.

23. Ice
The heavier water displaces the lighter ice, so ice floats to the top.
One consequence of this is that lakes and rivers freeze from top to bottom.
This allows fish to survive even when the surface of a lake has frozen over.
If ice sank, the water would be displaced to the top and exposed to the colder temperature, forcing rivers and lakes to fill with ice and freeze solid.