1. Water Objectives: Describe the structure of a water molecule
List and describe water’s unique properties

2. Think, Pair, Share Why is water so important to life?
What makes water so special?

3. Water and Living Things
Water is the most abundant molecule in living things.
Water has special traits that make it important to life.

4. Polarity
Water is a compound made up of polar molecules. A polar molecule is a molecule in which opposite ends have opposite electric charges.
Negative charge
Positive charge
Electrons spend more time near the oxygen atom since its greater number of protons exerts a greater pull on the electrons. This imparts a slight negative charge to the oxygen portion of the water molecule. By default, the hydrogen atoms are left with a slight positive charge.

5. Hydrogen bonding
Hydrogen bonds form when a covalently-bonded H+ is attracted to a negatively-charged atom in a neighboring molecule.
Because of its polarity and hydrogen bonding, water has unique characteristics that benefit living things.

6. Online Activity 4.4
How are 2 water molecules like 2 magnets?

7. Characteristics of water:
Water’s Life-Supporting Properties
Cohesion
Adhesion
High Specific Heat Capacity
Low Density of Ice
Ability to Dissolve Other Substances

8. Characteristics of water:
Cohesion
Refers to the tendency of molecules of the same kind to stick together.
This is stronger for water than other liquids.
Example:

9. Characteristics of water:
Adhesion
Refers to the attraction that occurs between unlike molecules.
Example: Water is able to travel against gravity up a tree trunk.

10. High Specific Heat Capacity
Refers to the quantity of heat required to raise the temperature of a unit mass of the substance by one degree C.
Water requires a lot of heat to change its temperature.
Example:

11. Characteristics of water:
Low Density of Ice
Density refers to the amount of matter in a given amount of space.
Ice (solid form of water) is less dense than water (liquid form).
As a result, when a pond or lake freezes, the top ice layer floats on top of the liquid layer. Organisms can live in the liquid layer.
Example:

12. Characteristics of water:
Ability to Dissolve Other Substances
Solution: a uniform mixture of two or more substances.
Solvent: the substance that dissolves the other substance and is present in greater amounts.
Solute: the substance that is dissolved by the solvent.
Water is the main solvent inside all cells, in blood, and in plants.

13. Conclusion: Based on the notes, answer these two questions again.
Why is water so important to life?
What makes water so special?