Polarity Of Water
- In a basic water molecule that contains two hydrogen atoms and one oxygen atom, the hydrogen atoms form a polar covalent bond with the oxygen atom.
- The polarity of each water molecule attracts other molecules
- Polar molecules are hydrophilic (water loving- substances)
- What makes the molecule polar is the positive and negative bonds
The positive charges of the hydrogen atoms bond with the oxygen atom- no net charge
Surface Tension of Water
- Surface tension is the property of the surface of water which allows the liquid to resist an external force
- Due to surface tension, it allows insects and other objects the "walk" across the water as long as they don't break the surface of the water molecules.
The water molecules bond together and create strong bonds. The surface of the molecules is where objects can walk across.
This Water Strider takes surface tension to it's advantage so it can walk on water. The water molecules bond together where their is only air above. This creates tension and a membrane like surface is created for the water strider to walk upon. The legs have tiny hairs that repel water and capture air. When they repel the water they can stand on the water and can move easily.
- Cohesion is the attraction of molecules of the same kind
- Water molecules contain strong cohesive forces because of their ability to form hydrogen bonds with one another.
- Cohesive forces are responsible for surface tension
The dome shaped water droplets on the spider web contain cohesive properties, tendency to stick to one another.
- Water molecules usually stick to one another but in other cases they stick to different kinds of molecules, this is called adhesion.
An example of adhesion is measuring the meniscus of water. The water molecules "climb" up the glass and stick to it causing the shape of the meniscus.