Ozone is made of three oxygen atoms bound together and which is written by chemists as O₃. It looks something like this illustration.

The Ozone molecule shown here has three balls held together with two sticks. The balls each represent the nucleus (or core) of an oxygen atom, and the sticks are the chemical bonds that hold the atoms together.

Here is another way to draw a molecule of ozone. In this picture the "balls" represent electron clouds. The electron clouds from each atom are squeezed together.

What do these pictures mean?

Both of these pictures gives an idea of what the molecule looks like, just with a little different view. The difference is like the difference between a picture of a house and a cutaway view of the house. One lets you see only the outside and the other lets you see into the house. Both pictures show the same house just in a different way. No one really knows how the molecule would really look because it is much too small to be seen. To give you an idea of the size of this molecule just imagine placing 5 million of the molecules side-by-side. It takes this many ozone molecules to be as wide as a human hair! If you had a ball the size of the period at the end of this sentence you could place 3000 trillion molecules of ozone gas into it!

Ozone is a chemically reactive gas. This means that it "attacks" other chemicals. A good example of ozone attacking another chemical can be seen by placing a rubber band near an ozone source, such as a photocopy machine. You will see that the rubber band will develop a hard "crusty" surface and visible cracks in it. When ozone chemically reacts it is destroyed in the process. Ozone can also attack the chemicals in your eyes and the lining of your nose making them sore and can even give you a headache and make it difficult to breathe. Ozone is a pollutant in many large cities. The interesting thing about this is that ozone does not come out the exhaust pipe of cars, the smoke stacks of power plants, or from any other pollution source. Instead it is produced in polluted air by a combination of pollutants that chemically react when sunlight shines through the air. The ozone found in polluted cities is not natural and is harmful to the health of the people who breathe it. This web site is not about ozone pollution in cities but rather it is about natural ozone found about 10-50 km above the Earth's surface in a layer called the "Stratospheric Ozone Layer" or simply "Ozone Layer".