As you know, the electron cloud surrounds the nucleus of an atom. The electron cloud is literally an assembly of electrons. By Coulomb electrostatic force, the each member of electron avoids each other very strongly. In fact, if two of them were to be about the same position in space, then infinitely srtong Coulomb force will tear them decidedly. Overlapping of the de Broglie wave of each electron is strictly inhibited. Therefore, even an electron cloud of an atom cannot be seen to be a static peaceful thing. In this seemingly static electron cloud, every electron is busily steering its course in order never to encounter with any other electron. Thus, though it seems static from outside, the inner working of an electron cloud is actually very busy. We cannot image it like the usual cloud floating in the sky or a lump of cotton. An electron cloud even at rest must have dynamic motions always in it.
This is my personal current view. What is yours, Sir?
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