1. The Properties of Water
primarily due to polarity

2. Terms to Know polarity hydrogen bond cohesion adhesion surface tension
capillary action

3. Water Most abundant naturally occurring liquid
Liquid at most Earth temperatures
Unlike most liquids – it expands when frozen
The lower density of ice allows it to float (4°C most dense)

4. Water  H2O As we know - water is neutral
But because the O atom is larger than the H atoms – electrons spend more of their time nearer the oxygen This gives water a slight overall charge
That charge is called polarity

5. Polar Bonding Polarity really does allow bonding
They are hydrogen bonds and they are very weak
They last for fractions of a second
Continuously break and reform
Polarity really does allow bonding
They are hydrogen bonds and they are very weak
They last for fractions of a second
Continuously break and reform

6. Forces due to polarity
Cohesion
Adhesion

7. The natural attraction of a water molecule to other water molecules
is called cohesion

8. Cohesion
Can be seen as water droplets form

9. The attraction of a water molecule to another polar molecule is adhesion
Molecules such as soil and clay (dust)
Surfaces like glass or paper straws
Certain clothing fibers and … animal hair

10. Adhesion
Can be seen as water droplets form on the spider web (another polar surface)

11. Two simple properties associated with polarity are
Capillary Action
Surface Tension

12. Capillary Action
We know that gravity is ALWAYS pulling on objects with mass
Yet water can move up a paper towel with relative ease - How can this happen?
Because the positive and negative charges in the paper attract the polar water molecules (adhesion)
This property of adhesion is called capillary action

14. Surface Tension
Inside a drop of water polar water molecules attract to each other in a random fashion
At the surface of the drop, water does not attract to the air
A unified layer of molecules at the surface creates surface tension
There the water behaves like an flexible sheet allowing denser objects to “sit” on the surface

15. Surface Tension

16. surface tension capillary action
Review
Polarity  hydrogen bonding
cohesion adhesion
surface tension capillary action
Forces
Forces
Properties

17. Water Hydrophilic - having a strong affinity for water; tending to dissolve in, mix with, or be wetted by water Hydrophobic -lacking affinity for water; tending to repel and not absorb water; tending not to dissolve in or mix with or be wetted by

18. The End polarity