When you say that the electron acts as a wave, then the wave is the quantum mechanical wavefunction and it is therefore related to the probability of finding the electron at any point in space. It no longer makes sense to say that you have precisely determined both the position and momentum of such a particle. As you proceed downward in size to atomic dimensions, it is no longer valid to consider a particle like a hard sphere, because the smaller the dimension, the more wave-like it becomes. Important steps on the way to understanding the uncertainty principle are wave-particle duality and the DeBroglie hypothesis. Graphical interpretation of uncertainty principle Even with perfect instruments and technique, the uncertainty is inherent in the nature of things. This is not a statement about the inaccuracy of measurement instruments, nor a reflection on the quality of experimental methods it arises from thewave properties inherent in the quantum mechanical description of nature. There is likewise a minimum for the product of the uncertainties of the energy and time.
There is a minimum for the product of the uncertainties of these two measurements. The position and momentum of a particle cannot be simultaneously measured with arbitrarily high precision. Uncertainty principle The Uncertainty Principle