I have a question about Hybridization of orbitals of Electron-Domain Geometry. Basically it has been discovered that the "d" sub-shell of an electron configuration no longer is used when a atom has a super octet, meaning that is has more than 8 electrons. It used to be thought that the atom then put them in the open space in the "d" sub-shell of the configuration. However as of this year it has been show to not be true but it is still that way in my book (two years old). Can anybody here explain the theory of the extra electrons being in the "d" sub-shell? I never really understood it.