What is the purpose of electrons orbiting around an atom?
Electrons have many purposes, but primarily, they serve as the balance of the positive charge in the nucleus. Everything in nature tends toward greater stability, or lower energy, therefore if you have a net positive charge in the nucleus, you must have something to balance it out. This is taken care of by the electrons. Also, electrons are the source of bonding in all types of bonds. Whether it be the sharing of electrons in a covalent bond or the attraction by charges caused by fluctuations in electrons in ionic bonds, it is the electrons that control this. If this were up to the nucleus, every reaction would be a nuclear reaction, and that is something that is not feasable.