Write the limitation of aufbau principle
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Answer:
Explanation:The Aufbau principle cannot be used to predict electron configuration of atoms on ionization. In other words, it does not tell us which electrons are to be removed when an ion is formed form an atom. For example, the configuration of Fe based on Aufbau principle is 1s2 2s2 2p6 3s2 3p6 4s2 3d6. It has been experimentally confirmed by spectral and magnetic studies than tFe2+ has configuration 1s2 2s2 2p6 3s2 3p6 3d6 and not 1s2 2s2 2p6 3s2 3p6 4s2 3d4. It means that ionization results in the loss of 4s electrons in preference to 3d electron even thought the 3d were the last to be added in building up the configuration of Fe atom. It means that in Fe2+ ,3d has lower energy than 4s which is contrary to Aufbau order of filling. This can be said of any transition element on ionization.