 Welcome back to Kids Fun Science. My name is Ken. Today's experiment is surface tension, drops of water on a penny. As always, adult supervision is required. What you need for this experiment is a penny, a pipette, or an eyedropper, and dish soap. So now you make a prediction on how many drops of water I'm able to put on top of one penny. The object of this experiment is to see how many drops of water you can put onto a single penny before it spills over. So we will see how many I'm getting here. And as we do it, I will explain the science behind it. So as I continue to drop drops of water on the penny, I'm going to tell you the science behind this. There are two different properties at work in this experiment. Cohesion and surface tension. Cohesion is the attraction of like molecules to one another. In this case, the like molecules are the H2O molecules in the water drops. Surface tension is a special term we use to describe cohesion between water molecules. Water's cohesions and surface tension are special because of the hydrogen bonds. Hydrogen bonds are formed by the hydrogen atoms in one molecule being attracted to the oxygen atoms in another molecule. The cohesion and the surface tension of the water becomes apparent when the drops of water you add to the each penny reach to the edge of the penny. Once the water has reached the edge, you begin to see a bubble or dome of water forming on top of the penny as seen here. The bubble shape is a result of the water molecules clinging to one another in an optional shape. So it gets to that point where it can't handle anymore. 25 drops is not bad. Oh, I have got over 30. So I'll try it one more time here and I will speed it up to see how many drops I can get. The dome that they're clinging around making that shape, that dome, it's just like the bond.