Question

Which of the following compounds of elements in group ${\text{IV}}$ is expected to be most ionic?
A.${\text{PbC}}{{\text{l}}_{\text{2}}}$
B.${\text{PbC}}{{\text{l}}_{\text{4}}}$
C.${\text{CC}}{{\text{l}}_{\text{4}}}$
D.${\text{SiC}}{{\text{l}}_{\text{4}}}$

Answer 1

The compounds made up from the combination of positive and negative ions are known as ionic compounds. The extent of the ionic and covalent character of the bond is predicted by the fajan’s rule and the electronegativity difference of the elements.

Complete step by step answer:
Ionic compounds, the compounds composed from the interaction of positive and negative ions are known as ionic compounds. Basically the cations are formed from metals, metals lose electrons and form cations and nonmetals gain electrons to form anions.
There are two ways to predict whether the bonds are ionic or covalent.
The first way is the difference in the electronegativity of elements. The electronegativity difference is directly proportional to the ionic character. Hence the elements from the far left and far right groups form ionic compounds.
The second way is to predict from Fajan’s rule. Fajan’s rule has three postulates which helps in predicting the nature of bonds. If the size of the cation is smaller and the size of anion is larger than the bond has more covalent characters. If the charge is greater on the cation, it has more covalent characters, the alkali and alkaline earth metals form mostly ionic compounds. These are some roughly explained postulates of Fajan's rule.
So from the above statements we understood that we have to take the compound with less charge on its cation and anion. Hence we can see that ${\text{PbC}}{{\text{l}}_{\text{2}}}$ is the only compound with less charge on its anions and cations. It has $+ 2$ oxidation state while the other compounds have $+ 4$ oxidation state, so ${\text{PbC}}{{\text{l}}_{\text{2}}}$ is most ionic among all of the given compounds.
Hence, option A is the correct answer.

Note:
The elements with lower oxidation states have more ionic characters and the elements with higher oxidation states have less ionic characters according to fajan’s rule. The size of cation and anion also affects the ionic and covalent nature of the compounds.