# Hund's rule for comparing term symbol energies in excited state

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.

• 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 $s^2p^2\to s^1p^3$ May 3 '21 at 8:55
• But on subwhat shell are we going to apply the less than half or more than half filled subshell rule? May 3 '21 at 14:00
• 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
– Paul
Jun 19 '21 at 8:19