whenever i have the air on and im stopped at a light or parked there is this buzzing/rattling noise coming from the engine. im pretty sure its the compressor but is that normal or a sign of wear?

 

Kind of a clattering?
Probably wear, but might be low on refrigerant.
If is is low on refrigerant, you should fix the leak. Usually you can find the leak by looking for a dirty spot on the AC system. Dirt will stick to the oil that leaks out along with the refrigerant.
AC work requires special tools, like a gauge set and vacuum pump, at a minimum. Better to take it to an AC shop.