Does true randomness exist?

Let's take the movement of gas in a container as an example.

Are their movements pre-calculated or its just a random path that they are taking? In this case, I think the random path makes more sense.

Of course gases would migrate to lower pressures system, gravitiy etc but let's take all of these out of the equation.

If I have a single Oxygen atom at the center of a vacuum container at t=0, where would it be at t=1? Truth is, we can never know because randomness is at work. We as humans can only predict this motion.