1. Unit 1: Chemistry of Life

2. Properties of Water

3. Goals
Examine the properties of water and why it is so important for life:
Surface tension
Adhesion
Cohesion
Polarity pH

4. Water Molecule
“Mickey Mouse” molecule

5. Water Molecule Oxygen has a slight negative charge
Hydrogen has a slight positive charge
This makes water a polar molecule
Uneven distribution of electrons

6. Water molecule Hydrogen bond – forms between two water molecules
Gives water many of its special properties
Polarity causes attraction between water molecules-magnets

7. Cohesion vs. Adhesion
Cohesion-attraction between molecules of same substance
Water sticks to water
Adhesion-attraction between molecules of different substance
Water molecules “stick” to a surface
Capillary action-in plants and surface tension

8. Solute vs. Solvent Solute-substance getting dissolved (salt, sugar)
Solvent-substance in which the solute dissolves (water)
VS.
Water is the greatest SOLVENT in the world!!!!!!!!

9. Density Definition: The degree of compactness of something
Formula: density= mass/volume
Temperature is a measure of how much energy molecules have
Water at room temp has MORE energy than cold water
The density of room temp water is LESS because there is more energy which causes the molecules to be further apart
When water cools down, there is LESS energy so the molecules move closer together
When water reaches freezing, electrostatic forces push molecules further way from each other and form ice

10. So Why does Ice float? Water is LESS dense in ice form!
Why is this important for life on Earth?