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All lanthanide elements form trivalent cations, Ln 3+, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum (La) to lutetium (Lu). These elements are called lanthanides because the elements in the series are chemically similar to lanthanum .
The lanthanide contraction is the greater-than-expected decrease in atomic radii and ionic radii of the elements in the lanthanide series, from left to right. It is caused by the poor shielding effect of nuclear charge by the 4f electrons along with the expected periodic trend of increasing electronegativity and nuclear charge on moving from left to right.
Due to the large ionic radius and great electropositivity of La 3+, there is not much covalent contribution to its bonding and hence it has a limited coordination chemistry, like yttrium and the other lanthanides. [40] Lanthanum oxalate does not dissolve very much in alkali-metal oxalate solutions, and [La(acac) 3 (H 2 O) 2] decomposes around ...
A direct consequence is that, during the formation of coordination bonds, the REE behaviour gradually changes along the series. Furthermore, the lanthanide contraction causes the ionic radius of Ho 3+ (0.901 Å) to be almost identical to that of Y 3+ (0.9 Å), justifying the inclusion of the latter among the REE.
Lanthanide and actinide aqua ions have higher solvation numbers (often 8 to 9), with the highest known being 11 for Ac 3+. The strength of the bonds between the metal ion and water molecules in the primary solvation shell increases with the electrical charge, z, on the metal ion and decreases as its ionic radius, r, increases. Aqua ions are ...
Lanthanides can be used because their small size (ionic radius) gives them the ability to replace metal ions inside protein complex such as calcium or nickel. The optical properties of lanthanide ions such as Ln(III) originate in the special features of their electronic [Xe]4f n configurations. [ 4 ]
Ionic radius, r ion, is the radius of a monatomic ion in an ionic crystal structure. Although neither atoms nor ions have sharp boundaries, they are treated as if they were hard spheres with radii such that the sum of ionic radii of the cation and anion gives the distance between the ions in a crystal lattice .
Ionic potential; Ionic radius; L. Lanthanide contraction; P. Pauling's rules; V. Van der Waals radius; W. Wigner–Seitz radius This page was last edited on 30 ...