In the early universe, shortly after the Big Bang, the conditions were extremely hot and energetic. At such high temperatures, the energy levels of electrons were so high that they were not bound to individual atoms. Instead, they existed as free electrons, roaming independently.
As the universe expanded and cooled down over time, the energy levels of electrons decreased. At a certain point, the conditions allowed for the formation of neutral atoms. This occurred during a process known as recombination, where electrons combined with atomic nuclei to form stable atoms.
In neutral atoms, electrons occupy specific energy levels or orbitals around the nucleus. The electrons are not continuously getting closer to the nucleus over time, as they are already bound to specific energy levels determined by the quantum nature of the atom.
The distribution of electrons around the nucleus is determined by the atom's electronic structure, which is governed by quantum mechanics. Electrons occupy different orbitals and energy levels based on their quantum numbers, which dictate their specific properties and positions.
While it is true that cooling of the universe allowed for the formation of neutral atoms and the binding of electrons to nuclei, it is important to understand that once electrons are in their stable atomic orbitals, their positions are not continuously changing or getting closer to the nucleus over time. Instead, they occupy specific energy levels and orbitals determined by the atom's electronic configuration.