Answer:
Symbolic representation of the hydrogen atom: nucleus (in red) and electron (in black the atomic orbital of the electron). The molecule would consist of two hydrogen atoms.
The hydrogen atom is the simplest atom that exists and the only one that admits an exact analytical solution from the point of view of quantum mechanics. The hydrogen atom is also known as a monoelectronic atom, because it is formed by a proton that is in the nucleus of the atom and contains more than 99.945% of the mass of the atom, and a single electron - about 1836 times less massive than the proton- "orbit" around said nucleus (although there may also be hydrogen atoms with nuclei formed by a proton and 1 or 2 more neutrons, called deuterium and tritium, respectively).
A pedagogical analogy of the hydrogen atom can be made with a Solar System, where the sun would be the only atomic nucleus and that has the largest amount of mass - specifically 99.86% of the Solar System - and in its planet orbit (Electron ) that would make up the rest of the mass of the System (protium atom (1H)). This makes hydrogen the simplest of all the elements in the periodic table of the elements.