Towards Quantum Mechanical Model of Atom

1, 2 and 3 are according to quantum theory but (4) is statement of kinetic theory of gases

Through Heisenberg's Uncertainty Principle, it's proven that you can't pin down where an electron is and how fast it's moving at the same time. The Bohr model did not look into this. The main reason for that thought was that it pictured electrons like little planets that would move in a loop around the nucleus. But that only works if you know both position and speed exactly. Nature doesn't let you do that. Add to it the fact that electrons also behave like waves, and the Bohr model just couldn't keep up. That's why scientists had to move on to the quantum model, which fits way better with how electrons actually act.