Sub shell electron configuration of ions?

In subshell electron configuration of ions, the electrons are distributed in the subshells of the ion according to the number of electrons it has gained or lost. For example, if an ion has gained one electron, the electron will be added to the subshell with the lowest energy level. The subshell electron configuration of ions can be represented using the noble gas notation, where the nearest noble gas element is used as a reference point for the electron configuration of the ion.