What do you understand by isoelectronic species? Name a species that will be isoelectronic with each of the following atoms or ions.
(i) `F^(-)` (ii) Ar (iii) `Mg^(2+)` (iv) `Rb^(+)`

Explanation

Ions of different elements which have the same number of electrons but different magnitude of the nuclear charge are called isoelectronic ions.
a. `F^(ө)` has `10 (9+1)` electrons. Therefore, the species nitride ion, `N^(3-)(7+3)`, oxide ion, `O^(2-)(8+2)`,neon, `Ne (10+0)` ,sodum ion, `Na^(o+)(11-1)`,magnesium ion, `Mg^(2+)(12-2)` ,alumininum ion,`Al^(3+)(13-3)` etc., each one of which contains `10` eleectrons, are isoelectronic with it.
b. `Ar` has `18`electrons. Therefore, the species phosphide ion, `P^(3-)(15+3)`, sulphide ion, `S^(2+)(16+2)`,chloride ion, `Cl^(ө)(17+1)`, potassium ion, `K^(o+)(19-1)`, calcuim ion, `Ca^(2+)(20-2)`etc., each one of which contains `18` electrons, are isoelectronic with it.
c. `Mg^(2+)` has `10(12-2)`electrons. Therefore, the species `N^(3-),O^(2-),F^(ө),Ne,Na^(o+),Al^(3+)` etc., each one of which contains `10` electrons, are isoelectonic with it.
, iv. `Rb^(o+)` has `36(37-1)` electons. Therefore, the species bromide ion, `Br^(ө)(35+1)`, Krypton, `Kr (36+0)` and strontium `Sr^(2+)(38-2)`, each one of which has `36` electrons, are isoelectronic with it.