Question

The most favourable conditions for the formation of ionic bond are:
A.Small cation, large anion
B.Large cation, small anion
C.Large cation, large anion
D.Small cation, small anion

Answer 1

Hint: Ionic bonds are formed between an anion and a cation. The basic principle of ionic bonding can be understood as transfer of electrons from an electropositive ion to an electronegative ion.

Complete step by step answer:
-When a redox reaction or a ‘reduction-oxidation’ reaction takes place, atoms with lower ionization energy release electrons for atoms with higher electron affinity to accept.
-Ionization energy depends on the size of the atom. Due to shielding effect, the net nuclear charge on the valence electrons becomes weak. Because of this, the ionization energy of these atoms are lower. From this, we can conclude that atoms with larger size have lower ionization energies, hence are better electron donors, i.e. they are better cations.
-Electron affinity also depends on the size of the atom. As discussed earlier, shielding effect weakens the net nuclear charge on the valence electrons. But if the size of the atom is small, then the shielding effect will be much lower as compared to larger atoms, due to decrease in the number of shielding inner electrons. This increases the net nuclear charge, and in turn increases the electron affinity of the atom.
-From the points discussed above, we can conclude that the most favourable conditions for the formation of ionic bonds are large cation and small anion.

Hence, Option B is the correct option.

Note:
Ionic bonds are mainly formed due to the transfer of atoms because of the higher degree of electrostatic force between the two combining atoms.