Experiment 3: 

"Attraction & Repulsion"

Surface tension is the tension of the surface film of a liquid. It is caused by the attraction of the particles in the surface layer by the bulk of the liquid. Surface tension forms an "invisible skin" in water that is enough to support an object that you would think would sink.

You Will Need:

A Shallow bowl filled with water

6 Toothpicks

1 Cube of Sugar

1 Small Piece of Soap (a drop of dish soap works too!)

A:

Step 1: Arrange the toothpicks in a circle in the bowl of water .

Step 2:  Carefully place the sugar cube in the center of the toothpick circle.

Step 3:  Watch as the toothpicks are attracted to the center of the bowl.

B:

Step 1:  Change the water in the bowl and arrange the toothpicks in a circle once again.

Step 2:  This time add your piece of soap (or drop of dish soap) to the center.

Step 3:   Watch the toothpicks move away from the center of the bowl.

The Science Fact: 

Sugar sucks up water, creating a current that carries the toothpicks with it toward the center of the bowl. The soap, however, gives off an oily film that spreads outwards. This film weakens the surface tension of the water and carries the toothpicks away with it.