moniatoms
Moniatoms is a hypothetical concept that refers to atoms composed of a single type of elementary particle. This term is generally used in theoretical physics and cosmology to describe certain early universe scenarios or exotic matter candidates. The idea is not that a single atom is made of only one electron or one proton, but rather that an atom could theoretically exist where all its constituent particles were identical, for instance, a hydrogen atom where the proton and electron were indistinguishable from each other.
In standard atomic theory, atoms are composed of a nucleus containing protons and neutrons, and electrons orbiting
Moniatoms are not observed in nature and are not part of the current Standard Model of particle