Five ideas in chemical education that must die: The atomic orbital conundrum

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Are 4s atomic orbitals preferentially occupied and ionised?

The third idea in our series is the notion that 4s atomic orbitals are preferentially occupied and preferentially ionised with respect to 3d orbitals in transition metal atoms. This idea is extremely pervasive even though it has occasionally been corrected in scientific and chemistry education literature. As many chemistry students are quick to realise, the notion that 4s orbitals are preferentially occupied and also ionised makes little sense since the preferential occupation of 4s orbitals seems to suggest that the electrons falling into these orbitals should not be the first to be ionised.

Inspired by the book This Idea Must Die Eric Scerri explores outdated chemical concepts, in this article: The atomic orbital conundrum.

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