* Element: A substance made up of only one type of atom (e.g., oxygen, nitrogen).

* Compound: A substance made up of two or more different elements chemically combined (e.g., water - H2O).

* Mixture: A combination of two or more substances that are not chemically bonded. Each substance retains its own properties.

Air is a mixture of different gases, primarily:

* Nitrogen (N2): About 78%

* Oxygen (O2): About 21%

* Argon (Ar): About 0.9%

* Carbon dioxide (CO2): A small percentage, but increasing

* Other gases: Trace amounts of neon, helium, methane, etc.

These gases are not chemically bonded together, they are simply mixed. You can separate them using physical methods like fractional distillation.