Which two parts make up the nucleus of a atom?

In the most widely taught atomic model, the atom's two main parts are the nucleus and the electron cloud. The nucleus is the ultra-dense core of the atom, containing large, heavy protons and neutrons (large and heavy are of course comparative measures - they are both infinitesimal). The electron cloud is the area around the nucleus in which the negatively charged electrons orbit (possibly) the nucleus. Think of the Sun and the Planets and you've got the right idea, only it's a bit more complicated with the Atom. The electrons do not move in their orbitals exclusively; when the system gains or loses energy they are rife to jump from one to another, emitting or absorbing light. Also, the electrons' positions cannot be known certainly. Thus, the electron cloud - an area in which electrons might be orbiting.