* Oxygen (O2): We breathe it!
* Nitrogen (N2): Makes up the majority of the air we breathe.
* Carbon dioxide (CO2): A greenhouse gas produced by respiration and burning fuels.
* Argon (Ar): An inert gas found in the atmosphere.
* Helium (He): A noble gas used in balloons and for other purposes.
Important note: While some elements exist as single atoms (like Helium) at room temperature, most gases are made up of molecules.
