Water has unique properties primarily due to its polarity. Polarity arises because oxygen is more electronegative than hydrogen, giving water molecules an overall slight charge. This polarity allows water molecules to form hydrogen bonds, contributing to properties like cohesion, adhesion, surface tension, and capillary action. Water is the most abundant naturally occurring liquid on Earth and is unusual in that it expands when frozen.

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  H 2 O 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. Review Polarity  hydrogen bonding cohesion adhesion surface tension capillary action Forces Properties Forces

17. The End polarity