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Introducing Atoms and Molecules

What Are Atoms and Molecules?, Matter, The Way Things Are, Differences

Think about a clear, fresh glass of water. What is the water made of? The answer is atoms and molecules. A single glass of water contains millions and millions of them. Each one is too small to see by itself.

Microworlds You can't see them, but there are many millions of tiny atoms and molecules in this glass of water.

What Are Atoms and Molecules?

All things are made of these tiny bits, or particles. Atoms are like tiny balls. Molecules are groups of atoms joined together. All the stuff around us is made of atoms and molecules. Water, metal, plastic, wood, air, and even living things are all made of atoms and molecules.

Microworlds All the stars, moons, and planets in space are made up of atoms and molecules—including our own planet, Earth.


Scientists have a name for all this stuff. They call it matter. The different kinds of matter are known as materials. For example, water, wood, metal, plastic, and stone are all materials.


It takes a lot of atoms and molecules to make matter. One cup (8 ounces/240 milliliters) of water contains about 24,000 billion billion (24,000,000,000,000,000,000,000) atoms.

Microworlds The water in this river can flow and swirl. The metal and concrete bridges are fixed and firm.

The Way Things Are

Think about that glass of water again. What can you do with water? You can slosh it, stir it, or swirl it around. You can drink it. You can pour it through your fingers.

But you can't do these things with a metal spoon. A metal spoon is hard, and it keeps its shape. Metal and water are both made from atoms and molecules. But they are completely different. How can that be?


There are many types of atoms. When different atoms join together, they make different types of molecules. Different materials are made up of different atoms and molecules. This makes them behave in different ways.

This book is about what atoms and molecules are and how they make up the amazing, ever-changing world around us.

Microworlds Food is made from atoms and molecules. So are all living things, including humans.

Additional topics

Science Encyclopedia for KidsMicroworlds