AP EAMCET201922 Apr 2019Morning ShiftChemistryClassification of Elements and Periodicity in PropertiesActual
Which one of the following is the correct order of ionic radii?
Options
- A( Pr ³⁺ > Gd ³⁺ > Tm ³⁺ )
- B( Pr ³⁺ < Gd ³⁺ < Tm ³⁺ )
- C( Pr ³⁺ > Tm ³⁺ > Gd ³⁺ )
- D( Pr ³⁺ < Tm ³⁺ < Gd ³⁺ )
Correct answer
A. ( Pr ³⁺ > Gd ³⁺ > Tm ³⁺ )
Step-by-step solution
In (4 f )-series, as the atomic number increases from ( La ) to ( Lu ) the atomic and ionic radii decreases gradually. This decrease in atomic and ionic size from lanthanum to lutetium is due to lanthanide contraction. Hence, the correct order of ionic radii of given element is ( (101 pm ) Pr ³⁺ > (94 pm ) Gd ³⁺ > (87 pm ) Tm ³⁺ )