Which one of the following groupings represents a collection of isoelectronic species

• Atomic Structure

Which one of the following groupings represents a collection of isoelectronic species? (At. nos.: Cs-55, Br-­35)

1. Ca²⁺, Cs⁺, Br
2. Na⁺, Ca²⁺, Mg²⁺
3. N^3-, F^–, Na⁺
4. Be, Al³⁺, Cl^–

Answer

Isoelectronic species are the neutral atoms, cations or anions of different elements which have the same number of electrons but different nuclear charge. N^3-, F^– and Na⁺ each have 10 electrons.

The correct option is C.