103 Solids, Liquids, and Gases-High

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 that 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 and substances. Each has its own properties. These properties may include color, size, temperature, and a particular shape or 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 a thing? In this book, you will learn about the objects and substances all around you as well as 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 that takes up a small amount of space. The water in a swimming pool takes up a lot of space. You are made of matter. If you are sitting in a chair, no one else can sit in that same space at the same time. No two things can occupy the same space at the same time. Before you pour a glass of milk, the glass is full of air. When you pour milk into the glass, the milk pushes the air out of the glass. As you drink the milk, air moves back into the glass.

Types of Matter Matter comes in three main forms. These forms are called 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, plants, and decorations. These things each have a specific shape. They also take up a specific amount of space. Matter that takes up a specific amount of space, has a specific shape, and keeps that shape when moved from place to place is called a solid. Even the tank is a solid. You can move it from one place to another without it changing shape. When the tank is moved, it takes up the same amount of space.

The water that the fish swim in does not keep the same shape when moved from one place to another. But if the water were moved into a different-shaped container of the same size, 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. Matter that does not keep the same shape when moved from place to place and cannot be squeezed into a smaller space is a liquid.

Objects can move through liquids, and liquids can move around objects. When a liquid is poured, it fills the container from the bottom. It also takes the shape of the container and forms a flat surface on top. Notice how the water fills the space inside the two fishbowls on the previous page. Even though the sides are different shapes, the top surface of the water in both is flat. Do You Know? Even though we 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, just as liquid matter does. But each little solid grain of sand keeps its shape; it is the position of each tiny grain of sand that changes. The sand doesn't immediately settle and have a flat top.