States of Matter
Vocabulary
Read the vocabulary terms to understand the reading better.
Gas
A gas is a material that can expand to fill any container it is put into and does not have a definite volume.
Liquid
A liquid is a flowing material that takes the shape of whatever container it is put into and has a definite volume.
Matter
Matter is anything that has mass and takes up space.
Solid
A solid is an object that keeps its shape and has a definite volume.
Volume
Volume is the amount of space an object takes up.
Anything that has mass and takes up space is matter. Matter can exist in three different states—solid, liquid, or gas. Each of these states has different properties.
Solids

A solid holds its shape. For example, a rock is a solid. If you put a rock in a box, the rock will not take on the shape of the box.
Solids have a definite volume. The volume of a solid does not change. (Remember that volume is the amount of space that matter takes up.) A solid always takes up the same amount of space.
Liquids

Liquids take on the shape of the container they are in. For example, a fishbowl and an aquarium have different shapes. When you pour water into each container, the water takes on the shape of the container.
Liquids have a definite volume. Even though the shape of a liquid can change, it always takes up the same amount of space. Imagine that you fill a fishbowl with water. Then, you pour the water into an aquarium. The shape of the water changes, but its volume does not.
Gases

Most gases are invisible. We cannot see the air we breathe, but air is made up of different gases. When wind blows, we can feel these gases moving against our skin. Steam from a boiling kettle is a gas.
Gases do not have a definite shape. They take on the shape of the container they are in.
Gases do not have a definite volume. If you put a small amount of gas into a large container, the gas will spread out to fill the container.
Comparing Properties of Solids, Liquids, and Gases
Use the table to describe and compare the shape and volume of each state of matter.
State |
Shape |
Volume |
Solid |
holds its shape |
has a definite volume |
Liquid |
takes on the shape of its container |
has a definite volume |
Gas |
takes on the shape of its container |
does not have a definite volume |
To learn more about the states of matter, watch the video by Learn Bright on YouTube.
Show What You Know!
Complete some questions about the reading selection by clicking “Begin Questions” below.