1. The Properties of Water

2. Structure
Water is one oxygen atom bonded to two hydrogen atoms. H2O is the formula.
Each end of the molecule has a slight electrical charge.
The oxygen end has a slight negative charge and the hydrogen end is slightly positive.
Molecules with a charge are
considered polar molecules.

3. 3. The + and - attract each other, so the water molecules tend to “stick” to each other.

4. Surface Tension
A. The tightness across the surface of the water caused by the polar molecules pulling on each other.

5. Capillary Action
The attraction of water molecules to other surrounding materials.
B. This allows water to “cling to” and “climb” up materials.

6. Water, the Universal Solvent
Solution
A mixture that forms when one substance dissolves another.
The solvent is the substance doing the dissolving. Water is the solvent.
Water dissolves substances by the positive and negative charges attracting the positive and negative charges of the substance and tearing it apart.

8. C. Water dissolves other polar substances.
1. Solids - soap, salt
2. Liquids - bleach, alcohol
3. Gases - oxygen, CO2
D. Water cannot dissolve non-polar substances (those without charges).
1. Wax
2. Oil

9. Changing State
A. Water is the only substance on Earth that commonly exists in all three states, solid, liquid, and gas.
B. Melting - solid to liquid
Freezing - liquid to solid
C. Boiling - liquid to gas
Evaporation - liquid to gas only at the surface of the liquid
Condensation - gas to liquid

10. Gas Liquid Temperature Solid Energy Boiling Condensation Melting
Freezing
Solid
Energy

11. Ice Floats
A. Ice is less dense than water.
B. Density is how tightly packed together the molecules are.
C. When water freezes, the molecules move slightly farther apart, making ice less dense.
D. Less dense things float.

12. Specific Heat
A. The amount of heat needed to raise the temperature of a certain mass of a substance by 1º C.
B. Water has a high specific heat. It takes a lot of heat to raise the temperature of water.
C. This is why the oceans are still cold in June and yet are warm in September.