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An introduction to gases and the air we breathe.
Can you catch something that you cannot see? Even though your room looks empty, it is actually filled with something very important right now!
Everything in our world is made of matter. Some matter is hard like a toy (a solid). Some matter is wet and flows like juice (a liquid). But gas is a very special kind of matter! A gas does not have its own shape. Instead, it spreads out to fill up whatever space it is in. If you put a gas into a small bottle, it fills the bottle. If you let it out into a big room, it will spread out until it fills the entire room!
Quick Check
What does a gas do when you put it inside a box?
Answer
It spreads out to fill the whole box.
Did you know that you are swimming in gas right now? The air all around us is actually a mixture of different gases. We cannot see the air, but we know it is there because we breathe it in to stay alive. When you blow into a balloon, you are catching air from your lungs and trapping it. The air pushes against the sides of the balloon, making it grow bigger and round shape!
1. Take empty balloon. 2. Blow air from your mouth into the balloon. 3. Watch as the balloon grows. The gas (air) is spreading out to fill the inside of the balloon!
Quick Check
Is the air around us a solid, a liquid, or a gas?
Answer
Air is a gas.
Most gases are invisible. This means we can see right through them, like looking through a clear window. Even though we can't see air, we can feel it. When the wind blows against your hair, you are feeling the gas in the air moving and bumping into you. It is like an invisible blanket that covers the whole Earth!
1. Hold a piece of paper in front of you. 2. Wave your hand very fast toward the paper. 3. The paper moves! This happens because you are pushing the invisible gas (air) against the paper.
1. Imagine someone is baking cookies in the kitchen. 2. You are in your bedroom, but you can smell them! 3. This is because the yummy-smelling gas from the cookies spreads out through the whole house until it reaches your nose.
What does a gas do in a room?
Which of these is a gas?
True or False: You can usually see the air around you.
Review Tomorrow
Tomorrow, try to remember: If you blow air into a bag, what does the air do inside that bag?
Practice Activity
Go outside or stand near a fan. Close your eyes and feel the air hitting your skin. Remind yourself that you are feeling a gas!