Classification of Elements and Periodicity in Properties

Classification of Elements and Periodicity in Properties

Question

The correct sequence which shows decreasing order of the ionic radii of the elements is

  • Al3+ > Mg2+ > Na+ > F- > O2-

  • Na+ > Mg2+ > Al3+ > O2- > F-

  • Na+ > F- > Mg2+ > O2- > Al3+

  • O2- >F- > Na+ > Mg2+ >Al3+

Answer

D.

O2- >F- > Na+ > Mg2+ >Al3+

O2-, F-, Na+, Mg2+,Al3+ are isoelectronic species (10 electrons each)
Cation having a positive charge is smaller in size than neutral atom whereas anion having a negative charge is larger in size than neutral atom.

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