Question
Why do boron and aluminium halides behave as Lewis acids?
A.
Both halides $$\left( {M{X_3}} \right)$$ can accept electrons from a donor to complete their octet.
B.
Both halides $$\left( {M{X_3}} \right)$$ can donate a pair of electrons.
C.
Both halides $$\left( {M{X_3}} \right)$$ are covalent polymeric structures.
D.
Both halides $$\left( {M{X_3}} \right)$$ react with water to give hydroxides and $$HCl.$$
Answer :
Both halides $$\left( {M{X_3}} \right)$$ can accept electrons from a donor to complete their octet.
Solution :
Both boron and aluminium in their trihalides $$\left( {M{X_3}} \right)$$ possess six electrons in their valence shell. To complete the octet they can accept a lone pair of electrons acting as Lewis acids.