1. Properties of Water

2. The Unique Properties of Water
Water is a very unusual substance
It has many properties that differ from those of most other familiar substances
It is H20, meaning every water molecule has 1 atom of Oxygen and 2 atoms of Hydrogen

3. Specific Heat
Compared to other substances, water requires a lot of heat to increase its temperature
(Think of a hot sandy beach, but cool ocean water)
Specific heat: the amount of heat needed to raise the temperature of a certain substance by 1 degree Celsius
Water has a high specific heat

4. Polar Water is a polar molecule
A polar molecule is a molecule that has electrically charged areas
Hydrogen +
Oxygen –
The positive hydrogen ends of one water molecule attract the negative oxygen ends of nearby water molecules. As a result, the water molecules tend to stick together

5. Because it’s Polar…
Many of water’s unusual properties occur because of the attraction among polar water molecules
The properties of water include capillary action, surface tension, the ability to dissolve many substances, and high specific heat

6. Solution vs. Solvent
Solution – a mixture that forms when one substance dissolves another
Solvent – the substance that does the dissolving
In most cases, the solvent is water
AKA: Universal Solvent

7. Universal Solvent
Water is called the “universal solvent” because it dissolves almost anything!
The charged ends of the polar water molecule attract the molecules of other polar substances

8. Cohesion vs. Adhesion
Cohesion - The tendency of water molecules to form weak bonds and stick together Adhesion - The tendency of water to stick to other substances (besides itself)

9. Surface Tension
Surface Tension: the tightness across the surface of water that is caused by the polar molecules pulling on one another
* caused by cohesion
This explains how you can skip a rock or spiders can walk across water’s surface

10. Surface Tension
The Basilisk lizard makes use of the high surface tension of water to accomplish the incredible feat of walking on water's surface. 
It can't actually walk on water; rather, it runs on water, moving its feet before they break through the surface.  Take a look:
Miracle Lizard

11. Capillary Action
Capillary action: the combined force of attraction among water molecules and with the molecules of surrounding materials
* caused by adhesion
Allows water to stick to the inside of a straw, move through materials with pores, and cling to fibers of materials like cloth and paper

12. Buoyancy Buoyancy – the ability to float (this is how boats float!)
Water and other fluids exert an upward force called the buoyant force that acts on a submerged object
Buoyant Force – acts in the direction opposite to the force of gravity, so it makes an object feel lighter
- an object will sink if its weight is greater than the buoyant force

13. Hydrophobic vs. Hydrophilic
Hydrophobic – molecules that are repelled by water -literally means “fear of water” -usually non-polar, so they are not attracted to water’s charges -example: oils Hydrophilic - molecules that are attracted to water - literally means “water loving” -typically polar molecules that are charged -example: salt or anything that dissolves in water

14. Amphipathic Molecule
Amphipathic Molecule - a molecule that contains both polar and nonpolar regions
Very important in the human body

15. Changing of States
Water is the only substance on Earth that commonly exists in all of these different states

16. Density of Water D= m/v
In water's liquid form, hydrogen bonding pulls water molecules together.  As a result, liquid water has a relatively compact, dense structure.  Liquid Water and Hydrogen Bonding
As water freezes into ice, the molecules become frozen in place and begin to arrange themselves in a rigid lattice structure
Ice and Hydrogen Bonding

17. The solid ice crystal actually has large holes in it. 
There are fewer molecules in a given volume of ice than in liquid water!
In other words, ice is less dense than liquid water and will float on the surface of the liquid!
HOW CRAZY IS THAT!?!

18. Lattice Structure of Ice Water
Check out how the bonding is different for the solid and the liquids…
Lattice Structure of Ice Water
FYI…The normal pattern for most compounds is that as the temperature of the liquid increases, the density decreases as the molecules spread out from each other. As the temperature decreases, the density increases as the molecules become more closely packed. This pattern does not hold true for ice as the exact opposite occurs.