Why are some electron configurations different than expected from the Aufbau diagram?
1 Answer
Filled subshells (or sublevels) and half-filled subshells tend to be more stable than partially filled (but not half) subshells.
Explanation:
Having one electron in each of the three p orbitals, for a total of three electrons is more stable than having four electrons in the p subshell, in which one p orbital contains two electrons and the other two contain one electron.
You can see this in the electron configurations of many of the transition metals. For example, Molybdenum (Mo), atomic number 42, has the empirically determined electron configuration
