First of all, most of the electron density will always be concentrated encircling the nuclei, since nothing lowers the potential energy more than having positive and negative particles close by (see the red small balls at the carbon positions in Fig. ). The structural chemical bond is therefore a matter mainly of the remaining valence electrons. As can be seen in Fig. , due to the attraction to other nuclei and some kinetic energy interference, the valence electrons are concentrated between the atomic centres, creating the almost universal structural pattern of the chemical bond.