How to make bubbles

Bubbles! How are they made? Why are they round? You can blow bubbles with any mixture of soap and water, but add a "secret" ingredient and you'll get bigger and stronger bubbles! Keep reading to find out more about bubbles, and to see our recipe!

Water is made up of lots of tiny molecules. The molecules are attracted to each other and stick together. The molecules on the very top of the water stick together very closely to make a force called surface tension. Surface tension is what caused the water to rise up above the rim of the glass in the experiment – the water molecules stuck together to make a dome instead of spilling over the side. Why didn't the dome break when you stuck your finger through it? Why didn't the water spill over the glass? Well, the surface tension was strong enough that it just went around your finger. The water molecules still stuck to each other and nothing spilled! What happened when you put your soapy finger into the water? The soap on your finger broke the water's surface tension and some of the water molecules didn't stick to each other any more and they were pushed out of the glass!

The force of surface tension also creates bubbles. In plain water, the surface tension is strong and the water might make some bubbles, but they will not last very long and they will be very small, because the other molecules in the water will pull on the bubbles and flatten them. Soap needs to be mixed with the water to make bubbles that can float through the air. When you add soap, the water becomes flexible, sort of like elastic, and it can hold the shape of a bubble when air is blown into it.