Also please note, and I repeat myself that I argue there is a great difference between "really hard to predict" and "physically impossible to predict for any being, based on our own notion of the universe".
If it "means nothing in practice", and can be true/not true regardless of whether it is possible (even in theory) to test it - then I assume that it is unrelated to science and you are using it in a philosophical sense?
Turing machines are deterministic. Enumerating all Turing machines is deterministic. Whether any given Turing machine will terminate is unpredictable (the Halting problem).
Unpredictability does not entail nondeterminism, although distinguishing the two is not necessarily always possible.
Paraphrasing, the theoretical image of an atom, as well as the set of atoms and other particles - is perfectly deterministic. But the chaos theory talks about the real world, not the theoretical framework.