Question

Discuss the consequences of lanthanide contraction.

Answer 1

Consequences of lanthanide contraction :
(i) Basicity of ions : Due to lanthanlide contraction, the size of Le ions decreases regularly with increase in atomic number. Decrease in size of $L{a}^{3+}$ ions increase the covalent character between $L{a}^{3+}$ and $O{H}^{-}$ ion in $Ln(OH{)}_3$. Since the order of size of $L{a}^{3+}$ ions are
$L{a}^{3+}>C{e}^{3+}.......L{a}^{3+}$
(ii) There is a regular decrease in their ionic radii
(iii) Regular decrease in their tendency to act as reducing agent, with-increase in atomic number.
(iv) due to lanthanide contraction, second and third rows of d-block elements (transition elements) are quite close in their properties.
(v) Dub to lanthanide contraction, these elements. occur together in nature minerals and are difficult to separate.