Why is FeCl3 a Lewis acid?

##"FeCl"_3## is a Lewis acid because it can accept an electron pair from a Lewis base.

##"Fe"## is in Period 4 of .

Its is ##"[Ar]4s"^2"3d"^6##. It has eight .

In order to obtain a ##"[Kr]" ##configuration, it can add up to ten more electrons.

In ##"FeCl"_3##, the three ##"Cl"## atoms contribute three more to make a total of 11.

The ##"Fe"## atom can easily accept more electrons from an electron-pair donor.

For example,

##"Cl"^"-" + "FeCl"_3 → "FeCl"_4^"-"##

Since ##"FeCl"_3##can accept electrons, ##"FeCl"_3## is a Lewis acid.