I have been looking at electron configuration and understand the use of hund's rules, the Aufbau principle and the Pauli exclusion principle but am having difficulty with a question that has come up in a text book I am reading.
It says to find the ground state of tin (Z=50).I have calculated and checked that this leaves two remaining electrons in the 5p shell and that you ignore the filled shells as they contribute nothing towards calculations.
Iv worked through it and using the rules specified above and found that the lowest energy available (ground state) points to a triplet D state, but in the book it simply says that this is not possible due to the Pauli exclusion principle and doesn't explain further.
I am not sure how this relates to the quantum numbers and am wondering if it is due to the m_l quantum number??