Discover: Floating Paper Clips

This activity has you explore the property of water called surface tension.  The attraction between molecules is stronger at the water's surface.

It is strong enough to hold up water striders, a type of insect, so that they can walk on water. Their feet even make indentations on the water’s surface! This is because of water’s surface tension.

Water forms beads on the surface of a waxy plant leaf. This is because of water’s surface tension.

Did you know?

Because water molecules bunch together at the surface, it is easier to move under the water rather than at its surface.



  Try This!

Place a glass on a plate and fill the glass to the top with water. (If a little spills over, that's okay... just wipe it up!) Then, carefully add pennies (or nickels or dimes) to the glass by slipping them gently over the edge of the glass.

If you have difficulty, try again! If you drop the coins in too quickly, you will break the surface tension of the water! Add coins slowly enough so that you can produce a bulge of water above the rim of the glass. At some point, adding a coin will cause the bulge to break and the water will spill. This bulge occurs because of water’s surface tension. Those particles of water on the rim of the glass have bonds that keep them holding together even as you add more pennies. How many pennies were you able to add before the water spilled over?








Can a paper clip float on water?


Materials
  • cup
  • water
  • toothpick
  • fork
  • paper clip
  • liquid soap

  Notebook

Click to download the instructions for this activity. Save to your Chemistry Notebook.

  Check Your Answers

Once you have completed this activity, check your answers below. 

 Describe or draw what you observed:

 Paperclip dropped into water
 Paperclip sinks to the bottom.
 Paperclip placed on water
 Paperclip floats on top.
 Many paperclips placed on water
 Paperclips float and start to group together.
 Toothpick with dish soap in water
 Paperclips are pushed away or apart from where the toothpick is placed.
  1. Surface tension allows a paperclip to be suspended on the surface.
  2. Soap can be added to break the surface tension.

Pixabay
Fire ants are highly specialized insects that live in colonies. Normally, they live on the forest floor, but they have an incredible adaptation to survive floods. The colony can construct a living raft supported by the surface tension of the water. View this BBC Video of them doing just this: Ants create a lifeboat in the Amazon jungle.