The coordination sphere is [Fe(CN)₆]⁴⁻, and the counter ion is K⁺ in the complex K₄[Fe(CN)₆]. The entire coordination compound is enclosed in square brackets.

The oxidation number of the central atom in a complex is defined by considering the charge it would have if all ligands and shared electron pairs are removed. It is represented by a Roman numeral in parenthesis following the coordination ...

Homoleptic complexes, like [Co(NH₃)₆]³⁺, involve a metal bound to only one kind of donor group. Heteroleptic complexes, such as [Co(NH₃)₄Cl₂]⁺, feature a metal bound to more than one kind of donor group.

The lanthanoid contraction causes the radii of the third transition series elements to be very similar to those of the corresponding second series elements. The nearly identical radii of Zr (160 pm) and Hf (159 pm), resulting from the lanthanoid ...

The lanthanoid contraction is caused by imperfect shielding of one electron by another in the same sub-shell. While the decrease in atomic radii is not quite regular, M³⁺ ions exhibit a more regular contraction. This is attributed to the imperfect ...

The lanthanoid contraction refers to the overall decrease in atomic and ionic radii from lanthanum to lutetium. It is a unique feature in the chemistry of the lanthanoids and has far-reaching consequences, particularly in the third transition series.

Lanthanoids closely resemble each other more than ordinary transition elements in any series. They exhibit only one stable oxidation state, providing an excellent opportunity to examine the impact of small changes in size and nuclear charge along the series.

The f-block consists of the lanthanoids and actinoids. Lanthanum, closely resembling lanthanoids, is typically included in discussions of the lanthanoids, often denoted by the general symbol Ln.