Everything around us is made of atoms and molecules. Surprisingly, atoms and molecules are made up mostly of empty space. Here's a very simple experiment to prove that water molecules contain a whole lot of nothing.

Here's what you'll need:

Here's what to do:
Fill the cup to the brim with hot tap water. Make sure the surface is bulging. Without dipping the teaspoon in the water, CAREFULLY add a teaspoon of sugar to the water. Don't stir! Repeat several times.

The sugar molecules dissolve and fit into the empty spaces between the water molecules. That's why the water in the cup doesn't spill out.