Diagram representing the structure of the atom. An atom consists of one or more electrons (blue) that whirl about the tiny, central nucleus. The nucleus consists of protons (red) & neutrons (green), held together by the strong nuclear force. The number of electrically positive protons balance the number of electrically negative electrons to make the atom neutral overall. The atom shown is lithium, which has 3 electrons, 3 protons, & 4 neutrons (only 3 of which are shown). The orbits of the electrons are as traditionally represented; in reality, electron orbits are more eccentric, & much further out from the atom's nucleus.