Question

Which of the following is electron deficient?

• A. $CaC{l}_2$
• B. $B{F}_3$
• C. $A{l}_{2}C{l}_6$
• D. $CC{l}_4$

Answer 1

Answer: (B)

$B{F}_3$

The species of which the central atom's octet is not complete are termed as electron deficient species.

$\Rightarrow Ca{Cl}_2$ is ionic compound

$Ca{Cl}_2⟶\left[{Ca}^{2+}\right]+2\left[{Cl}^{-}\right]$

Both ${Ca}^{2+}$ & ${Cl}^{-}$ have complete octet

$\therefore Ca{Cl}_2$ is not electron deficient

$\Rightarrow$Generally compounds of group $13$ elements are electron deficient.

For example $B{Cl}_3,Al{Cl}_3$ etc

$\Rightarrow B{F}_3$ is electron deficient species as B-atom has only $6$ electrons around.

$\Rightarrow {Al}_2{Cl}_6$ is dimerised form of $Al{Cl}_3$

In this case, dimerisation takes place to complete the octet.

$\Rightarrow C{Cl}_4$ is also electron precise as $C$ atom has it's octet complete.