Transition element

(Under construction)

A transition element is a chemical element element whose atomic electron configuration has an incomplete d sub-shell, that is part of the electron configuration is (nd)k, with  1 &le; k &le; 9 and n the principal  quantum number. Also ionized atoms with an incomplete d sub-shell are transition elements.

A strict application of this definition would describe lutetium (Lu) as a transition element because it has a singly occupied 5d orbital in its ground state, but it is a lanthanide according to IUPAC.

Below the naturally occurring transition elements are shown in two tables. The elements in Period 7 are man-made [except for Actinium (Z = 87)] and not shown.

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