Avogadro's principle is a principle rather than a [[Scientific method|law]] (a summary of experience) because it depends on the validity of a model, in this case the existence of molecules. Despite there now being no doubt about the existence of molecules, it is still a model-based principle rather than a law. | Avogadro's principle is a principle rather than a [[Scientific method|law]] (a summary of experience) because it depends on the validity of a model, in this case the existence of molecules. Despite there now being no doubt about the existence of molecules, it is still a model-based principle rather than a law. |