1. Air We talk about “air” all of the time, but what really is it?
Air is a gas that is made up of a combination of other gases
We can’t see it with our naked eye, but it is all around us on earth
It does not exist in space because there is no gravitational pull keeping it together

2. The Main Components (Elements) of Air
Dry air is made up of the following gases:
Nitrogen (the largest part, around 78%)
Oxygen (21%)
Argon, Carbon Dioxide, Water Vapor (all help make up the last 1%) there are other gases present that we will not cover
There is more water vapor present in certain parts of the world than others.

3. 3 Properties of air
Air is matter. Just like things that we can see and touch, air is also matter. This is because it meets three requirements:
Property #1. Air takes up space. Even though we can’t see it or always feel it, air occupies space, meaning it takes up room.

4. Air takes up Space Proof that air takes up space:
Fill your cheeks with air. Poke them without opening your mouth. The air inside takes up space, making your cheeks puff out
Fill an empty balloon with air – watch it expand. This is because the air is taking up space.
Place a ping pong ball in a tub of water. Flip an empty cup upside down. Place the cup over the ping pong ball and push the ball to the bottom of the tub using the air trapped inside the cup

5. 3 Properties Property #2. Air exerts pressure.
Air experiences the pull of gravity, creating pressure on everything below it. This is called atmospheric pressure.
Air wants to stay in equilibrium – in balance with itself. When air pressure changes in one area air will flow from high air pressure to low air pressure
The air on earth is like water in the ocean. It exerts pressure on everything around it, but those objects exert pressure, as well.

6. Air Pressure How can we prove that air exerts pressure?
Fill a ziploc bag with air. Push your hands against either side of the bag until it pops. This shows that the air was exerting pressure against the bag and forced the bag to open
Grab a glass bottle with a small opening. Place a burning piece of tissue paper in the bottle and place a hard boiled egg on the opening of the bottle. Watch as the egg is pushed through the opening. This happens because the air pressure inside the bottle was changed by the increased heat and the air outside of the bottle wanted to balance it out, thereby pushing the egg into the bottle so that it reach equilibrium again

7. Air Pressure
How much pressure are you under? Earth's atmosphere is pressing against each square inch of you with a force of 1 kilogram per square centimeter (14.7 pounds per square inch). The force on 1,000 square centimeters (a little larger than a square foot) is about a ton!
Why doesn't all that pressure squash me? Remember that you have air inside your body too, that air balances out the pressure outside so you stay nice and firm and not squishy.

8. Air Pressure

9. 3 Properties Property #3. Air has mass. What does this mean?
Air actually weighs something, even though it doesn’t feel like it to us.
We can prove this by:
Using a scale, place one empty balloon on one side, and a balloon filled with air on the other. The one filled with air should lower the scale, showing that it has mass

10. Air can be Compressed
The fact that air can be compressed is NOT one of the properties. The three properties prove that air is matter, and not all matter can be compressed.
Air takes up space, but this space can be compressed (squished) into a smaller place when enough force is applied. If it is compressed too much, air will exert enough pressure bacck to potentially burst or cause a reaction.

11. Examples of Air being Compressed
A balloon filled with air
Tires (on a car, bike, etc.)
Aerosol cans (hairspray, house cleaners, canned whipped cream, etc.)
Oxygen tanks