Atomic structure. Computer artwork representing a single atom of beryllium (symbol: Be). This is the traditional way the structure of an atom is depicted, showing electrons orbiting in paths around a central nucleus. Beryllium contains four electrons (variously coloured), and a nucleus which has four protons and five neutrons (not seen). The number of electrically positive protons balances the number of negatively charged electrons. This image is highly schematic. Scientists now believe that electron orbits are more eccentric and electrons inhabit a cloud of probability rather than moving in welldefined orbital paths (often called the Bohr model).