During the early stages of the universe, immediately after the Big Bang, the conditions were extremely hot and energetic. At this time, the universe was filled with a high-energy plasma consisting of free electrons and protons. It took a significant amount of time for the universe to cool down sufficiently for atoms to form.
Once the universe had cooled down to a certain temperature, a process called recombination occurred. Recombination refers to the binding of electrons to protons, forming electrically neutral hydrogen atoms. This process allowed the universe to become transparent to light, as photons were no longer scattering off free electrons.
When atoms form, the electrons occupy specific energy levels or orbitals around the nucleus. The behavior of electrons within atoms is governed by quantum mechanics. According to quantum mechanics, electrons cannot exist in the same energy level and orbital simultaneously due to the Pauli exclusion principle, which states that no two electrons can have the same set of quantum numbers.
So, if two atoms were perfectly aligned such that their electrons were in the same energy level and orbital, they would not merge or become part of each other. Instead, the electrons would repel each other due to the electromagnetic force and occupy separate energy levels and orbitals.
When atoms come together to form molecules or larger structures, such as solids or liquids, it is through a process called chemical bonding. Chemical bonding involves the sharing or transfer of electrons between atoms to achieve a more stable configuration. This bonding can result in the formation of new molecular entities with different properties from the individual atoms involved.
In summary, if two atoms were perfectly aligned such that their electrons occupied the same energy level and orbital, they would not merge or become part of each other. Instead, the electrons would repel each other, and the atoms would maintain their individual identities. The formation of molecules and larger structures involves chemical bonding, where atoms share or transfer electrons to create new entities.