Aristotle had nothing to do with the atomic theory, other than being against it. As far as antique atomism goes, the ideas is essentially what it is in modern science---matter consists of indivisible elementary particles. It doesn't matter much that what we call "atoms" do not fit the description (at the time of their modern theoretical (re)discovery it was thought they are elementary). This simple idea, without any further elaboration as to how "atoms" work, just the idea that they exist as such, is far more powerful than it seems at first sight. Feynman thought it was the most important piece of scientific knowledge about the universe, so much so that if all scientific knowledge would to disappear but we could choose one fact to preserve, he would choose the idea of atomic theory.

Indeed any scientist relying on Aristotle would do badly, and one of the reasons was because he was against atomism.