Which part of an atom orbits the nucleus?

The protons and neutrons are arranged in the nucleus in energy levels known as shells analogous to those of the electrons orbiting the nucleus. The number of protons in the nucleus determines the atom's atomic number and its position in the Periodic Table. See more at atom. read more

The electron! Each weighs 9.109 382 15(45) Ã 10 -31 kilograms (Kg) and has a charge precisely opposite of that of a proton. read more

A nucleus is part of an atom, so an atom cannot orbit a nucleus in the first place. If your question is what do the ELECTRONS orbit the nucleus in, it's empty space. read more