Chapter 3 · Matter and Energy
3.1In Your Room
6 min · two checks
Predict
Is the air in a closed room matter?
The idea
- Define matter.
- Point to matter that is easy to overlook.
Look around a room and almost everything qualifies: the desk, the glass, the water in the glass, the carbon dioxide you just exhaled. Matter is anything that has mass and takes up space. Light from the lamp is not matter. The warmth you feel is energy crossing the room. The air itself is matter even though you see through it; a full balloon weighs more than an empty one for that reason.
Chemistry begins by sorting this clutter. Some of it is a single substance, some is a mixture, some is in the middle of becoming something else. The next sections give the sorting rules. For now, the commitment is simpler: if you can put it on a balance and it occupies volume, it is in scope.
Keep these
- Matter has mass and volume.
- Gases are matter. Light is not.
- Energy is real and important, and it is not a kind of matter.