The electronic configuration of the transition elements is(n–1)d1−10ns1−2.(n–1) stands for penultimate shell and d-orbitals mayhave one to ten d electrons and n denotes valence s or the outermostshell which can have one or two electrons. Hence the basic differencein electronic configuration of transition metals is that their penultimateshell is incomplete and progressively filled and not the valence shell.