QS Study

Important consequences of lanthanide contraction are given below:

i) Basicity of ions

Due to lanthanide contraction, the size of Ln3+ ions decreases regularly with increase in atomic number. According to Fajan’s rule, decrease in size of Ln3+ ions increase 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 are

La3+ > Ce3+ …………… >Lu3+

ii) There is 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 transistion elements are quite close in properties.

v) Due to lanthanide contraction, these elements occur together in natural minerals and are difficult to separate.

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