is demonstrated in the oxides. The highest oxidation number in the oxides (Table . ) coincides with the group number and is attained in Sc O to Mn O . Beyond Group , no higher oxides of Fe above Fe O , are known, although ferrates (VI)(FeO ) – , are formed in alkaline media but they readily decompose to Fe O and O .
Besides the oxides, oxocations stabilise V v as VO + , V IV as VO + and Ti IV as TiO + . The ability of oxygen to stabilise these high oxidation states exceeds that of fluorine. Thus the highest Mn fluoride is MnF whereas the highest oxide is Mn O . The ability of oxygen to form multiple bonds to metals explains its superiority.
In the covalent oxide Mn O , each Mn is tetrahedrally surrounded by O’s including a Mn–O–Mn bridge. The tetrahedral [MO ] n- ions are known for V V , Cr Vl , Mn V , Mn Vl and Mn VII . + Mn O + CrO + V O + TiO V O CrO MnO + Sc O Ti O V O Cr O Mn O Fe O Mn O * Fe O * Co O * + TiO VO (CrO) MnO FeO CoO NiO CuO ZnO + Cu O Table . : Oxides of 3d Metals * mixed oxides Groups Oxidation Number .
How would you account for the irregular variation of ionisation enthalpies (first and second) in the first series of the transition elements?