Group 12 element precludes there being much common chemistry between mercury and gold, though there are similarities between mercury(I) and gold(I) such as the formation of linear dicyano complexes, [M(CN)]. According to IUPAC's definition of transition metal as "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell", zinc and cadmium are not transition metals, while mercury is. This is because only mercury is known to have a compound where its oxidation state is higher than +2, in mercury(IV) fluoride (though its existence is disputed, as later experiments trying to confirm its
Interstitial element Interstitial element An interstitial element is an impurity found in "pure" metals or crystals. The quantity of these elements affect the physical properties of the host material. They can be introduced during the manufacturing process. The most common interstitial elements in metals are hydrogen, carbon, nitrogen, and oxygen. These elements are small enough to fit between normal crystalline lattice locations. In contrast, those elements that replace locations in the crystalline structure are called substitutional elements. An example of the effects of interstitial elements on metal properties can be found in grade 1–4 titanium. Although the grades 1–4 are considered commercially