 Despite many searches, no elements in this region have been synthesized or discovered in nature.According to the orbital approximation in quantum mechanical descriptions of atomic structure, the g-block would correspond to elements with partially filled g-orbitals, but spin-orbit coupling effects reduce the validity of the orbital approximation substantially for elements of high atomic number.While Seaborg's version of the extended period had the heavier elements following the pattern set by lighter elements, as it did not take into account relativistic effects, models that take relativistic effects into account do not.