Characteristics of d-Block Elements

The d-block spans groups 3 to 12, all of which are metals, commonly called transition elements or transition metals. Positioned between the highly-reactive s-block and the comparatively less-reactive p-block groups 13-14, they form a kind of chemical 'bridge' between the two. Because most d-block elements possess partially-filled inner d-orbitals, they display a cluster of characteristic properties not seen in the s- or p-blocks: variable oxidation states (since electrons can be lost from more than one energetically-close subshell), paramagnetism (from unpaired d electrons), the ability to form coloured ions (from electronic transitions between split d-orbital energy levels), and usefulness as catalysts (partly because of this ability to shift between oxidation states). Zinc, cadmium and mercury are a notable exception within the d-block: their configuration $ns^2(n-1)d^{10}$ has both the outer s and inner d subshells completely filled, leaving no partially-filled d …