Lanthanoid contraction is the:
ADecrease in valency
BShrinkage during cooling
CSteady decrease in atomic and ionic radii of lanthanoids from La (Z=57) to Lu (Z=71) — due to poor shielding of one 4f electron by another
DDecrease in the temperature of lanthanoid metals
Answer & Solution
Correct answer: C. Steady decrease in atomic and ionic radii of lanthanoids from La (Z=57) to Lu (Z=71) — due to poor shielding of one 4f electron by another
**Lanthanoid contraction**: as Z increases across the lanthanoid series, **4f electrons are added but their poor mutual shielding** means effective nuclear charge increases more than expected → **radii decrease gradually** from La (~187 pm) to Lu (~173 pm).
Related questions
Among Sc²⁺, V³⁺, Mn²⁺ and Zn²⁺, which is paramagnetic with **5** unpaired electrons?All transition metal ions form complexes more readily than main-group metal ions. Which isWhich of the following ions is NOT coloured in aqueous solution?The general electronic configuration of actinoids is:Actinoids in general have which characteristic that distinguishes them from lanthanoids?Which lanthanoid is well known to exhibit the +4 oxidation state in aqueous solution as a A major consequence of lanthanoid contraction is:The most common oxidation state of lanthanoids is: