Water Makes up 70-90% of all living things Covers 3/4 of earth’s surface

Chemical Formula of Water H2O 2H2 + O2  2H2O Chemical Structure

Characteristics of Water Water is Polar Hydrogen Bonds High Surface Tension Adhesion Cohesion Universal Solvent Density Temperature Moderation

1. Water is Polar Water molecules are polar: Polar molecules have an uneven distribution of electrons The molecule has (+) and (-) end.

1. Water is Polar 1. Water molecules are polar: Polar molecules have an uneven distribution of electrons The molecule has (+) and (-) end.

Hydrogen Bonds The polarity of water results in Hydrogen bonding: weak bonds that are constantly broken/formed. Water molecules are held together by hydrogen bonds The positive hydrogen of one water molecule is attracted to the negative oxygen of another water molecule. The two atoms then ‘adhere’

2. High Surface Tension Water has high surface tension Application: Hydrogen bonds make it difficult to “break” through the surface of water. Application: Some organisms can “walk” on water

3. Adhesion Water molecules are adhesive. H2O Application: Water molecules stick to other surfaces Application: Water can travel up plant stems (capillary action). H2O

4. Cohesion Water molecules are cohesive Application: Water molecules stick together Application: Water molecules move as waves (affects temperature, dissolved gases, nutrient/microorganism distribution)

5. Universal Solvent Water is a universal solvent (dissolver). Universal Solvent: Creates a solution and can dissolve many different solutions Great solvent because it has positive and negative areas that attract ions Application: Water can carry minerals and nutrients with it through soils and in blood.

5. Universal Solvent And this is important because…? A universal solvent is important because it makes up many living organism’s bodies and will not create new substances when chemicals are added to it! Solvent: What is doing the dissolving Solute: What is being dissolved

Water = solvent Salt = solute

6. Density Ice is less dense than liquid water Application: Water expands when frozen Application: Ice floats on top of water, and insulates water below it, keeping it from freezing

7. Temperature Moderation Water heats up and cools down very slow Application Keeps our body temperatures constant Keeps the worlds temperature constant