Question

Amongst the following species, the maximum covalent character is exhibited by
(A) \[FeC{l_2}\]
(B) \[ZnC{l_2}\]
(C) \[HgC{l_2}\]
(D) \[CdC{l_2}\]

Answer 1

Hint: Covalent character depends upon both the anion and cation. According to Fajan’s rule, the cation with a small size and high positive charge and the anion with a greater charge shows the maximum covalent character.

Complete Step by Step Solution:
The periodic table is the representation of chemical elements arranged in the increasing order of atomic masses. These chemical elements were arranged in the vertical columns known as groups and horizontal rows known as periods.
The elements Ferrous, Zinc, Cadmium, and Mercury belong to the d-block, which is placed between the s-block and p-block elements. Whereas, ferrous and zinc belong to the same period. The elements zinc, cadmium, and mercury belong to the same group. The atomic size decreases along with the periods and increases along with the groups. Hence, Ferrous will have a small charge.

Out of the given compounds, all the anions are the same i.e.., chloride ions. The actions were different. A ferrous atom forms a small charge. Hence, the compound \[FeC{l_2}\] forms maximum covalent character as the anion chloride ion is the same in all the compounds, but the \[F{e^{ + 2}}\] will form a higher charge cation with a small size.
Option A is the correct answer.

Note: Chemical compounds can be formed by the interaction of an anion and cation. Hence, the size and charge of the cation and anion should be considered. As the opposite (greater size of action and small size of anion) leads to the formation of an ionic character.