Because of this fact, if either the d or f subshell is one electron short from either of these preferred configurations, an electron from a higher s subshell will generally drop to the required position in the respective d or f subshell.
Example:
Determine the electron configuration for gold.
The configuration according to the table is
However, in order to minimize total energy, one of the electrons will fill the d subshell in the fifth shell, so the final configuration is
