Animation of the structure of the 4dz2 orbital, one of the five 4d atomic orbitals. Orbitals contain an atom磗 electrons, which are found around the central atomic nucleus not seen. Each orbital can hold two electrons. This 4d orbital is a different shape to the other four, which have four symmetrical lobes see clips K002 8693_8695. An atomic orbital is a mathematical model of the location of an electron around an atomic nucleus. Electrons do not orbit the nucleus as might be imagined, but instead exist as a standing wave around it. The phases of the wave are arbitrarily coloured red negative and blue positive.