# How do you identify Lewis acids and bases?

Mar 30, 2018

Few steps below

#### Explanation:

1. Know the definition
Lewis acids- accept an electron pair
Lewis base- donate an electron pair

Now what you need to look for in the given compound, is whether the compound is capable of donating electron pairs or accepting them for example:

$A l B {r}_{3}$
Questions to be asked:
=>"Are there any unbonded electron pairs on the central atom?" =>"If yes, then this molecule can act as a Lewis Base"

=>"Is the valence shell of the central atom filled?" =>"If not, then this molecule can act as a Lewis Acid"
With these two questions, we can determine whether this molecule is a lewis base or acid, or you can always draw a Lewis Dot structure

So, Al is the central atom, which has 3 valence electrons and there are no unbonded electrons as one of each is bonded to each Br, however the valence shell of the central atom is not full, therefore this molecule can act as a Lewis acid.

You try:
$N {H}_{3}$

${O}^{- 2}$

$B {F}_{3}$