Question

The molecule in which an atom is associated with more than $8e^{-}$ is known as hyper valent molecule. All hyper valent molecules must have $d\pi -p\pi$ bonding but the molecule having back bonding need not have always $d\pi -p\pi$ bonding.
Which of the molecule is not hypervalent but completes its octet?

• A. $AlC{l}_3$
• B. $AlB{r}_3$
• C. $Al{F}_3$
• D. $B{F}_3$

Answer 1

The correct option is C $Al{F}_3$

$AlC{l}_3,AlB{r}_3,B{F}_3$ are covalent compounds. In all these molecules, central molecule has only six electrons in its valence shell. These complete their octet due to back bonding with the lone pair on the halogen. $Al{F}_3$, it is an ionic compound which consists of $A{l}^{3+}$ and $3F^{-}$.