Question

Write any two consequences of Lanthanoid Contraction.

Answer 1

1. Due to the close similarity in electronic configuration and ionic radii, the lanthanides have identical chemical properties, which make their separation difficult.
2. Due to lanthanide contraction, the size of Ln³⁺ ions decreases regularly with an increase in atomic number. According to Fajan's rule, a decrease in the size of Ln³⁺ ions increases the covalent character and decreases the basic character between Ln³⁺ and OH^– ion in Ln(OH)₃. Since the order of size of Ln³⁺ ions is La³⁺ > Ce³⁺ ... > Lu³⁺.