1. Water and Life
How the properties of water enable life to exist

2. Cohesion occurs when water molecules stick to each other
Cohesion occurs when water molecules stick to each other. Adhesion is when water molecules stick to other surfaces.

3. Adhesion allows water to stick to the veins of plants, and Cohesion allows the water to stay together as it travels through the veins.

4. Surface tension Is this cohesion or adhesion?

5. Solid water is less dense than liquid water: Ice floats!

6. Large bodies of water are “Heat Sinks”:
Maritime climates vs. Continental climates
Climate in San Francisco:
Climate in

7. Water is life’s solvent: it dissolves Salts and Sugars

8. Water is a polar molecule
As a result it can form Hydrogen bonds.
This gives water its unique properties.

9. Polar Covalent bonds:
One atom shares its electrons unevenly with another.
This forms a
Polar Molecule

10. In Polar Molecules, one end of a polar molecule is slightly negative while the other end is slightly positive.

11. Polar molecules are like magnets: When they come near each other, they form a weak attraction called a Hydrogen bond.
Weak attractions singularly
Strong when many are together
Help to hold together the 3D shapes of complex molecules (like DNA and enzymes)
In liquids, regularly form, break, and reform as molecules move
Easily broken by enzymes or a drastic change in conditions (heat, salinity, pH…)

12. Hydrogen bonds make water molecules sticky
Notice how the opposite charges of each water molecule are facing each other--

13. Hydrogen bonds can form between any two polar molecules.

14. Because of Hydrogen Bonds, Solid water is less dense than liquid (so it floats!)
Ice is less dense than water because the molecules lose the energy to break hydrogen bonds; there is more space between molecules.

15. Water is the Solvent of Life
Solutions form when polar molecules dissolve salts or other polar molecules
Solution, solvent, solute, Hydrophilic, Hydrophobic

16. In liquids, water can dissociate to form hydroxide (OH-) and hydrogen (H+) ions.

18. Summary
Water is a polar molecule because the oxygen end is slightly negative and the hydrogen end is slightly positive
Polar Molecules can form hydrogen bonds
Hydrogen bonds make water molecules sticky—causing cohesion and adhesion
These qualities allow life to exist

19. 1.The properties of water are extremely important to trees!!
Identify and explain each property of water a tree relies on.

20. 2.Like dissolves like: So, polar molecules will dissolve in other polar molecules.
Explain why nonpolar molecules, like lipids will not dissolve in water.