Next, use the photon energies to determine the valence orbital energies for both li and na. forlithium, the transition is from the 2p-to the 2s-orbital, and the 2s-orbital energy is –520.3 kj/mol. use this to find the energy of the 2p-orbitalsin li. for sodium, the higher-energy photon is emitted when the electron drops from one of the 3p-orbitalsto the 3s-orbital, while the lower energy photon is emitted when the electron drops from one of the 3d-orbitalsto one of the 3p-orbitals. use these facts, along with the known energy of the 3s-orbital(–495.8kj/mol), to find the energies of the 3p-and 3d-orbitals.