21 Gases Matter

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Gases Matter by ANNA PROKOS With the Editors of TIME FOR KIDS

CHAPTER 1 What Is Matter? Think about all the things on Earth. Everything that takes up space is called matter. Houses, toys, roads, lakes, plants, and animals are all made of matter. You are made of matter. The air you breathe is made of matter, too. There are three kinds of matter. Solids have their own shape. Liquids take the shape of what they are poured into. Gases have no shape. Sometimes you cannot see them. Air is made of gases. This book is about gases.

CHAPTER 2 Every Breath You Take Take a deep breath. You are now full of gas! Yet you cannot see it, taste it, or smell it. Air is made of gases. Gases are important for life on Earth. The deep breath you took is full of oxygen. Plants and animals need oxygen to live. Earth is the only planet that has enough oxygen for all living things. Oxygen is in air and water. But it is not the only gas we need.

CHAPTER 3 Blown Away The air you breathe out is different from the air you breathe in. The air that comes out is a mix of oxygen and carbon. Together, carbon and oxygen make a gas called carbon dioxide. Plants need carbon dioxide to make food. Plants give off oxygen into the air. It is the oxygen that humans— and all animals— breathe in. Plants and animals work together to make the gases they need.

CHAPTER 4 From Soil to Air, and Back Again Most of our air is made of a gas called nitrogen. Plants, people, and animals need nitrogen in order to live. But they cannot get it from the air. They must get nitrogen from the soil. The roots of plants take in nitrogen from the soil. When plants die, they become part of the soil. The nitrogen goes back to the soil, too.