In this topic you will learn how matter can be described and classified by its characteristics.

Not all things in the world are made of matter. Think about the color yellow, the month October, and the number 46. They are not matter. They are ideas. Matter is anything that takes up space, has mass, and has properties you can observe and describe.

Some properties used to describe matter include color, shape, size, texture, and hardness. One other property of matter is buoyancy. Buoyancy is the upward force of water or air on an object.

All matter has mass. Mass is the amount of matter making up an object. For example, a dictionary has more mass than a feather. Mass is measured in units called kilograms. Small masses are measured in units called grams. There are 1,000 grams (g) in a kilogram (kg). A balance is used to measure mass.

A book that you read, the water that you drink, and the helium that fills a balloon are three examples of states, or forms, of matter.

A textbook is an example of a solid. A solid is a form of matter that has a definite shape and takes up a definite amount of space. The particles of matter making up a solid are packed tightly together.

How would you describe the water you drink? Water is an example of a liquid. A liquid is a form of matter that takes up a definite amount of space and has no definite shape. In a liquid, the particles of matter move more than they do in a solid. They can change position and move past one another.

A gas is a form of matter that does not take up a definite amount of space and has no definite shape. If a balloon bursts, the particles of helium spread out into the air.

We use a lot of matter and, in turn, create a lot of trash. We can reduce the amount of things we use, use something again, and recycle. Recycling can take what we used and make it into something else.

Knowing about the properties of different matter helps people come up with ideas for using and recycling many things.