Electrons cannot stay inside the nucleus of an atom due to a fundamental property called the Heisenberg uncertainty principle. The uncertainty principle states that it is impossible to simultaneously determine the exact position and momentum of a particle with absolute precision.
In the context of an electron inside the nucleus, if the electron were to have a precise position within the nucleus, its momentum would be highly uncertain and vice versa. The uncertainty principle places limits on the precision with which we can know both position and momentum.
Additionally, the electron is governed by quantum mechanics, which describes particles in terms of wavefunctions. The wavefunction of an electron inside the nucleus would have to satisfy certain conditions, including being localized within a small volume. However, such a wavefunction would have extremely high kinetic energy, making it unstable and unlikely to exist within the confined space of the nucleus.
Moreover, the forces within the nucleus, such as the strong nuclear force, are responsible for binding protons and neutrons together. These forces are much stronger than the electromagnetic force between electrons and protons. Therefore, the electrons are primarily found in distinct energy levels outside the nucleus, forming electron clouds or orbitals around the nucleus.
In summary, the combination of the uncertainty principle, the properties of quantum mechanics, and the dominance of strong nuclear forces prevents electrons from staying within the nucleus of an atom.