5d(x2-y2) orbital, illustration. An electron orbital is a region around an atomic nucleus (not seen) in which one or a pair of electrons is most likely to exist. The 5d(x2-y2) orbital made up of twelve lobes, centred on the nucleus. The orbital is seen transparent at middle to show the axes of symmetry and the planar nodes and spherical nodes can be seen at right. Nodes are the regions in an atom with zero electron density and where the electron is least likely to exist. For the 5d(x2-y2) electron orbital, 5 indicates that it is the fifth energy level, and d indicates that the orbital is shaped like a four leaf clover (except the dz2 orbital), and (x2-y2) indicates the orientation of the orbital is in the xy-plane. The 5d(x2-y2) orbital can accommodate up to 2 electrons. It is part of the 5d shell, which contains five orbitals in total. The 5d orbitals are part of the 5 shell, which also contains one spherical 5s orbital and three bi-lobed 5p orbitals, both at a lower energy, and seven lobed 5f orbitals at a higher energy level (not seen).