Can electrons orbiting a stable atom e.g oxygen (that is not radioactive) be considered as perpetual motion. If no, why?

Electrons orbit around the nuclues all the time.

so... can this be counted as perpetual motion

Yup. Electrons whiz around the nucleus all the time. Like a factory that works none stop.

But recently i heard that atoms decay eventually!!!

Well, that i am not sure. Sorry man.

Entropy is a macroscopic property/concept, so the notion that perpetual motion of the first kind can't work doesn't apply on the atomic scale.

Oh ok. Thanx