Explain the factors favourable for the formation of Ionic Compounds.

Explanation

Factors that favour the formation of ionic bond :
a) Factors favourable for the cation formation :
i) Low IP : Atom with low IP loses electrons readily. So it forms cations readily. `K^(+)` (IP 496 KJ `mol^(-1)` ) ion forms readily than `Na^(+)` (IP 520 KJ `mol^(-1)`) ion.
(ii) Low charge on the ion : Formation of an ion with low charge requires lower IP than formation of an ion with high charge. Thus out of `Na^(+), Mg^(2_(+)) " and " Al^(3_(+))`, the ease of formation of these ions is `Na^(+) gt Mg^(+) gt Al^(3_(+))`.
iii) Large atomic size : The force of attarction between the nucleus and the valence electrons is less in case of larger atoms than in case of smaller atoms. So larger atoms can lose electrons more readily than smaller atoms.
Ex : `Cs^(+)` is formed more easily than any of the other alkali metal ions.
iv) Formation of cation with inert gas configuration : Cations with inert gas configuration are easily formed.
Ex : Out of `Ca^(2_(+)) " and " Zn^(2_(+)), Ca^(2_(+))` ion (2,8,8) is easily formed than `Zn^(2_(+))` ion (2,8,18) with pseudo inert gas configuration.
b) Factors favourable for anion formation :
i) High EN and high EA : An atom with high EN and high EA has a greater tendency to accept electrons and so it can readily form anion.
Ex : The ease of formation of anions is `F^(-) gt O^(2-) gt N^(-3)`
Small atomic size : Small atoms can hold strongly the electrons gained by it.
Ex : The order of ionic nature in halide ions is `F^(-) gt Cl^(-) gt Br^(-) gt I^(-)`.
F is the smallest and I is the largest atom, among them.
iii) Low charge on the ion : Stability of ion decreases with incease in its charge. Anion with low - ve charge is formed more readily than anion with high -ve charge.
Ex : `F^(-)` ion is easily formed than `O^(2-)` ion.