How can iron have an electronic configuration of 2, 8, 14, and 2?

The transition metals can make it difficult to understand electron configurations of elements. Iron is in the 1s2 2s22p6 3s2 4p6 4s23d6 configuration. The 4s orbitals must be filled before six electrons can be added to the 3d orbitals. The 3d orbitals belong to the n=3 orbitals, not the n=4 orbitals. You will therefore have 2 electrons inside the n=1 (1s), 8 in n=2 (2s & 2p) shell (8+6 =) 14 electrons within the n=3 (3s., 3p., and 3d), and 2 electrons within the n=4 (4s).

This isn’t enough fun, but you might still be interested in the electronic configuration of Neodymium and other Lanthanides. These shells have not filled to their full potential n=4, 5, and n=6.

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