Write the favourable factors for the formation of ionic bond.
The formation of ionic compounds primarily depends upon the ease of formation of the positive and negative ions from the respective neutral atoms. The formation of a positive ion involves the removal of electron(s), which depends on the ionization enthalpy of the atom, while the formation of a negative ion involves the addition of electron(s), which depends on the electron gain enthalpy.
Another favourable factor is the arrangement of the positive and negative ions in the solid, that is, the lattice of the crystalline compound. The ions formed attain stable noble gas electronic configurations and are stabilized by the electrostatic attraction between the positive and negative ions.
Explanation
According to the Kössel and Lewis treatment provided in the text, ionic bond formation depends on two main factors: the ease with which neutral atoms can form positive and negative ions (governed by ionization and electron gain enthalpies), and how these ions arrange themselves in the solid crystal lattice to maximize electrostatic stabilization.