Hi, I'm new to the forum, and I am very sorry if this has been asked before. I am Japanese and therefore my English might be a little bit awkward. I want to ask about term symbols and if they can be used to derive electron configuration in lanthanides. First of all, I do not major in Physics. I major in Chemistry. Therefore I am not very fond of physical or quantum physical aspect of lanthanides. The reason I am here is none of the people in my lab (not even the teachers) really know about term symbols. They know how they can use it, but they do not have the technical background that leads to the use of term symbols. 1) First of all, can term symbol be used as an effective way of deriving electron configuration? (If a term symbol is given for an atom, does it specify the electron configuration?). 2) In lanthanides, which should be considered: L-S coupling or j-j coupling (or something else)? 3) Does quantum number J (total angular quantum number) determine anything about electron configuration of an atom? I have found this true for some atoms (especially in lighter atoms or smaller number of electrons), but not for some other atoms. I was really confused about trivalent Europium (and Terbium) where there are 6 (or 8 in Terbium) electrons in 7 different orbitals. I can understand ground state term symbol 7F. The 4f orbitals should look like: (up)(up)(up)(up)(up)(up)() +3 +2 +1 0 -1 -2 -3 Parentheses are 4f orbitals, "up" means electron in its +1/2 state, and the numbers below the parentheses are azimuthal quantum numbers. However, does the total angular momentum quantum number "J" mean anything in this case? As long as total spin quantum number satisfies 7 = 2S + 1, all of the electron spins are +1/2, and due to Pauli principle, two electron cannot be in a same orbital unless the spin is changed. In that case, 7F1, 7F2, ..., 7F6 makes no sense at all. There are no possible combination of quantum number "l" and "s" that can satisfy "j" that makes up total quantum number "J". On the other hand, it made sense for 1D2 excited state of Praseodymium, because there are multiple possible state for spin because S = 0 (s1 = +1/2, s2 = -1/2 OR s1 = -1/2, s2 = +1/2), as well as the azimuthal quantum numbers, and the value of total angular quantum number can determine what kind of electron configuration it is: Pr(III) 1D2: (up)()()()(down)()() I am most likely having some terrible misunderstanding here and there, but because I really have no one to ask, I can't figure it out on my own. Please help me. Thank you very much.