Did you ever wonder what things are made of? Some objects are hard. Some are soft. Some things you can pour. The reason materials are different is because they are made of different bits called molecules. Molecules are so tiny that you cannot see them. Molecules are made of even tinier things called atoms. Two or more atoms link together to make a molecule. You and all things around you are made of molecules and atoms.

WHAT KINDS OF MOLECULES ARE THERE?

There are millions of different kinds of molecules. Some molecules are made of only one kind of atom. A molecule of oxygen gas is made of two oxygen atoms. Oxygen is a gas in air that all animals must breathe in order to live.

Most molecules are made of more than one kind of atom. One atom of oxygen and two atoms of hydrogen, for example, make a molecule of water.

Molecules come in all shapes and sizes. Water is a small molecule. Molecules that make up the plastic in a picnic fork are huge molecules made of many kinds of atoms.

WHAT’S THE DIFFERENCE BETWEEN MOLECULES?

The atoms in a molecule determine what material the molecule is. A change in just one atom can make a big difference. Two oxygen atoms make one molecule of pure oxygen gas. But one oxygen atom and one carbon atom make a molecule of carbon monoxide. Carbon monoxide is a deadly poisonous gas. If you add just one more oxygen atom to carbon monoxide, you get carbon dioxide, a harmless gas that plants need to make food.

WHERE DO MOLECULES COME FROM?

Some molecules are found in nature. Millions of natural molecules join together to make up the cells in plants and animals. The food you eat, the air you breathe, and the cotton clothes you wear are made of natural molecules.

Some molecules are made by scientists. The paint on your walls and the dye that colors your T-shirt come from molecules made by scientists.

 Source: Microsoft ® Encarta

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