Question

Why do boron and aluminium halides behave as Lewis acids?

• A. Both halides $\left( MX_{3} \right)$can accept electrons from a donor to complete their octet.
• B. Both halides $\left( MX_{3} \right)$ can donate a pair of electrons.
• C. Both halides $\left( MX_{3} \right)$ are covalent polymeric structures.
• D. Both halides $\left( MX_{3} \right)$ react with water to give hydroxides and HCl.

Answer 1

Answer: (A)

Both halides $\left( MX_{3} \right)$can accept electrons from a donor to complete their octet.

Answer 2

: Both boron and aluminium in their trihalides $(MX_{3})$ possess six electrons in their valence shell. To complete the octet they can accept a lone pair of electrons acting as Lewis acids.