Why SiF4 acts as a lewis acid.?

Question

sif4 is silicon tetraflouride..

Answer 1

Right, I see why it might seem weird, but the definition of a lewis acid is any substance that can accept a pair of electrons from a Lewis base.

The general form: A + :B → A—B

Here's how SiF4 acts like a Lewis acid:

SiF4 + 2F- → SiF62-

SF4 + F- → SF5-

It's taking that negative charge (electrons) from the F-

Be careful not to confuses these with the Bronsted-Lowery acids/bases, in which:

A base is a species that accepts protons (H+), while an acid is a species that dontates protons (H+).

Hope this helps.

Answer 2

SiF4 can accept electron pairs (the definition of a Lewis acid) and expand its "octet" to 12. An example is the complex ion, SiF6 2-.