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I am completely confused about how to write the electron configuration anything higher than Barium because there are so many inconsistencies and misconceptions about the 5d and 4f orbitals. I know that Lanthanum and Actinium have an outer orbital of d. Let's say I needed to write the configuration of Mercury. Wouldn't it be 1s2 (blah blah blah) 5d10 4f14? Because they always want to get to the lowest energy level? However, apparently, the correct way of writing it is 4f14 5d10...


marked as duplicate by ringo, Jan, bon, M.A.R., Wildcat Sep 30 '16 at 23:44

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Typically the noble gases are used as jumping off points to avoid a lot of tedium. It also puts more focus on the last few subshells which is nice too.

So Hg is $\ce{[Xe] 4f^{14} 5d^{10} 6s^2}$

  • $\begingroup$ the thing that I am confused about is the order in which people write the orbitals. shouldn't 5d10 be before 4f14? $\endgroup$ – user35487 Sep 30 '16 at 21:05
  • $\begingroup$ No. For the electronic configuration order by principle quantum number first, then by s, p, d and f. $\endgroup$ – MaxW Sep 30 '16 at 21:09
  • $\begingroup$ How do I find the principal quantum number? $\endgroup$ – user35487 Sep 30 '16 at 21:16
  • $\begingroup$ :-( For Hg you have 4f, 5d, and 6s. the digits 4, 5, and 6 are the principle quantum numbers. Remember the quantum numbers for an electron are are n, l, m, and s. The principle quantum number is the n value. The l value is the azimuthal number and gives the orbital type (s, p, d and f). en.wikipedia.org/wiki/Quantum_number#Traditional_nomenclatures $\endgroup$ – MaxW Sep 30 '16 at 21:38

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