Question

Considering $Be{Cl}_2,Mg{Cl}_2,Ca{Cl}_2$ and $Ba{Cl}_2$ predict which of the following statement is true?

• A. $Be{Cl}_2$ is least ionic out of the given chlorides
• B. Covalent character increases as the atomic number of the metal atom increases
• C. $Be{Cl}_2$ has the lowest melting point among the given chlorides
• D. All are highly ionic compounds

Answer 1

The correct option is A $Be{Cl}_2$ is least ionic out of the given chlorides

Ionic character of any molecule depends on the size of cation, anion and on the charges of cation and anion.

Here, in all the cases, anion is $C{l}^{-}$. Now, consider cations $B{e}^{2+},M{g}^{2+},C{a}^{2+}$ and $B{a}^{2+}.$

The charge is $+2$ in all the ions.

So, if we consider the size of cations, the increasing order of size is, $Be<Mg<Ca<Ba$ as we move down the group.

$Be$ is smallest in size. Hence according to Fajan's rule, $BeC{l}_2$ is the least ionic out of the given chlorides.