102 Solids, Liquids, and Gases-Mid

Solids, Liquids, and Gases Written by Charles and Natalie Barman

Introduction Look around you What do you see? Look at the book you are reading. Does it have a certain shape you can describe? What about the air you breathe Can you feel it, smell it, or taste it? What about water from a drinking fountain? Can you see it and feel it? Does it have a certain size or shape? Your world is made of many objects. Each has its own properties. These properties may include color, size, temperature, a certain shape, or a lack of shape. An object might feel rough or smooth, soft or hard, wet or dry. What are some other properties you can use to describe something? In this book, you will learn about the objects and substances all around you. You will also learn how these substances change.

Matter The things around you that take up space are known as matter. Your desk, the milk you drink, and the air inside a basketball are matter. They all take up space. A grain of sand is a small bit of matter. It takes up a small amount of space. The water in a swimming pool takes up a lot of space.

Types of Matter Matter comes in three main forms. Scientists call these forms the states of matter. Let's look at the picture of a fish tank. You can see gravel at the bottom of the tank. You can also see fish and decorations. Each of these things is a type of matter called a solid. They each have a specific shape. Their shape stays the same when moved from place to place. They also take up a specific amount of space.

The water that the fish swim in does not keep the same shape when moved from one place to another. If it were poured from the fish tank into a different-shaped container, it would take up the same amount of space. For example, if the water in the tank were moved into a large, round bowl, it would take the shape of the bowl. If the water in the tank were moved to a bowl smaller than the tank, the water would spill over the top of the bowl. The water in the tank cannot be squeezed into a smaller space.

If the bowl were bigger than the tank, the water from the tank would not expand to fill the bowl. Water is a type of matter called a liquid. Liquids do not keep the same shape when moved from one container to another. They also cannot be squeezed into a smaller space. Do You Know? Even though you can "pour" sand from one container to another, it is not a liquid. Why not? A pile of sand contains thousands of very small individual grains. Each small grain of sand is a solid. When you pour sand, it does take the shape of the container. But because each solid grain of sand keeps its shape, sand is a solid.