What orbits around the nucleus of an atom?

Electrons are the subatomic particles that orbit around the nucleus of an atom. Their arrangement around the nucleus is often visualized as being in various energy levels or shells, where they are constantly in motion. The nucleus itself, which contains protons and neutrons, is situated at the center of the atom. Electrons play a crucial role in chemical bonding and reactions, as their interactions with other atoms largely dictate the properties of elements and compounds.

While neutrons and protons reside in the nucleus, and nucleons refer collectively to protons and neutrons, it is the electrons that determine the atom's behavior in relation to other atoms. Thus, their orbital motion around the nucleus is fundamental to our understanding of atomic structure and chemistry.