All stuff is composed of smaller and smaller units called atoms. Neutrons, electrons, and protons make up the atomic nucleus. The nucleus of an atom is composed of protons and neutrons, and the electrons move in circular orbits around the nucleus. Atoms can join together in chemical bonds through the exchange of electrons. The molecular structure is produced in this way. The quantity of electrons exchanged or shared determines the sort of bond created. When two atoms share electrons, a covalent link is established; when one atom transfers electrons to another, an ionic bond is created.