Have you ever wondered what everything in the world is made from?
The answer is matter.
Matter is anything that takes up space and has mass.
There are millions of different things in the world, but there are just three different forms of matter.
- liquids, and
Everything in the world belongs to one of these three main forms.
You can probably think of hundreds of different solids and liquids.
Solids like stone and wood are hard and stay the same shape. Liquids like water and gasoline can flow from place to place.
But gases are different.
How do we use gases?
Like most gases, those in the air cannot be seen or smelled, and it is very difficult to make them stay in one place.
You can place a solid or a liquid in a cup or bowl, and it will stay there.
But gases must be kept in closed containers or they will escape.
There are many different kinds of gas.
Some are very useful.
Oxygen is an important gas. It is found in the air. It helps humans and animals to stay alive, and fires to burn.
Some gases come from under the ground.
They are used as fuels and are burned for heating and cooking.
One kind of gas helps balloons to float up in the air.
Other gases help divers to breathe deep down in the sea.
Gases are also used in factories to make other useful substances such as plastics, bleach, and medicines. They are used in the manufacture of fertilizers, explosives, and dyes.