This question was asked in an exam:

The lowest energy electronic state for excited state carbon atom is,
a. $^1D_2$
b. $^3D_1$
c. $^3D_3$
d. $^3D_2$

Although we have been taught Hund's rule for determining the relative energies for various term symbols in the ground state, I haven't read anything about the rules for excited state anywhere. I couldn't not find it in the book I use i.e. Atkins, Physical Chemistry.

I am really confused about how to solve this.

  • $\begingroup$ summarising (a) lowest multiplicity lowest energy (b) with a given multiplicity largest L lowest energy (c) Atoms with less than 1/2 filled shell lowest J lowest energy. Does not the excited state just means an extra electron 'upstairs' such as $s^2p^2\to s^1p^3$ $\endgroup$
    – porphyrin
    May 3 '21 at 8:55
  • 1
    $\begingroup$ But on subwhat shell are we going to apply the less than half or more than half filled subshell rule? $\endgroup$
    – Kashish
    May 3 '21 at 14:00
  • 2
    $\begingroup$ Hund's rules strictly assume LS coupling and application to excited states is not reliable. Of course you can try to apply them in a similar manner as for the ground state, but treat the outcome with caution $\endgroup$
    – Paul
    Jun 19 '21 at 8:19

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