Examples of double salts include carnallite (KCl.MgCl₂.6H₂O), Mohr’s salt (FeSO₄.(NH₄)₂SO₄.6H₂O), and potash alum (KAl(SO₄)₂.12H₂O), formed by combining two or more stable compounds in specific stoichiometric ratios.

Double salts, like carnallite or potash alum, dissociate completely into simple ions when dissolved. In contrast, complex ions, such as [Fe(CN)₆]⁴⁻ in K₄[Fe(CN)₆], do not dissociate into individual ions.

Werner proposed that octahedral, tetrahedral, and square planar shapes are common in coordination compounds. Examples include [Co(NH₃)₆]³⁺, [Ni(CO)₄], and [PtCl₄]²⁻ representing octahedral, tetrahedral, and square planar entities, respectively.

Coordination entities, within square brackets, are species formed by the central metal ion and its ligands. Counter ions, outside the brackets, balance the charge of the complex.

Coordination polyhedra describe the spatial arrangements of species within brackets in coordination compounds. They provide a framework for understanding the geometry around the central metal ion.

Werner’s theory, proposed in 1898, includes the concepts of primary and secondary valences. Primary valences are ionizable and satisfied by negative ions, while secondary valences are non-ionizable and correspond to the coordination number, determining the spatial arrangement of ions/groups around ...

Werner proposed that metals in coordination compounds exhibit primary and secondary valences. Primary valences are ionizable, satisfied by negative ions, while secondary valences are non-ionizable and satisfied by neutral molecules or negative ions, equal to the coordination number.

Alfred Werner was a Swiss chemist (1866-1919) who pioneered the understanding of coordination compounds. His contributions include formulating ideas about their structures and introducing the concepts of primary and secondary valences.

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 ...