It is often referred to as 'anomalous electron configurations' or 'unusual order of filling of orbitals' of a few elements e.g. Cr, Cu, Nb, Mo, Ru, Rh, Pd, Au etc.


1 Answer 1


The Wikipedia article clearly states :

[n+l rule] was suggested by Charles Janet in 1928...Janet "adjusted" some of the actual n + ℓ values of the elements, since they did not accord with his energy ordering rule, and he considered that the discrepancies involved must have arisen from measurement errors. In the event, the actual values were correct and the n + ℓ energy ordering rule turned out to be an approximation rather than a perfect fit...

  • $\begingroup$ Thanks for your greeting (while writing the answer I thought I was in SE Physics!)... But I didn't ask the question, so why are you saying about the title to me? $\endgroup$
    – Shub
    Jul 5, 2021 at 7:36
  • $\begingroup$ My mistake. (+1) $\endgroup$ Jul 5, 2021 at 7:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.