FIGURE 2.4 Two models of the A.A very simplified view ot he atom The central nucleus consists of protons and neutrons encircled by high-speed electrons B. This model of the atom shows electron clouds(shells) surrounding a central nucleus. The nucleus contains virtually all of the mass of the atom The remainder of the atom is the space in which the light, negatively charged electrons reside (the relative of the nuclei shown are greatly exaggerated.)