Classical and wave-mechanical model of electron

For large scale phenomenon,such as electronic trajectories in a vaccum tube,the classical model yields accurate results.For small scale systems,however such as an electron in an atom or in a crystal,the classical model treated by newtonian mechanics gives result which do not agree with experiment.To describe such subatomic systems properly it is found necessary to attribute to the electron a wavelike property which imposes restrictions on the exactness with which the electronic motion can be predicted.