# Lewis Acid-Base: Is BH3 a Base?

• terryds
In summary, the discussion is about whether BH3 is a Lewis base in the reaction with NH3. The conversation also involves defining Lewis acids and bases and the electronegativity of the elements involved. The suggested method to analyze the problem is to draw Lewis structures and determine the number of bonding electrons. Based on this, it is determined that NH3 is the Lewis base and BH3 is the Lewis acid. The conversation also mentions the importance of G.N. Lewis in this concept.
terryds

## Homework Statement

In the reaction with NH3, is specy BH3 a Lewis base ?

## Homework Equations

Lewis acid = electron acceptor
Lewis base = electron donor

## The Attempt at a Solution

H electronegativity = 2.1
B electronegativity = 2.0
N electronegativity = 3
Since N-H bond is more electronegative than B-H bond, NH3 is more electronegative than BH3 which means that NH3 is more easily to accept electron. So, NH3 is Lewis acid, BH3 is Lewis base

Is it correct??
My book says that NH3 is the base with no reason, and I doubt that.

A good way to analyse the above problem would be to draw the Lewis structures.There is a reason it is named after G.N. Lewis!

sidt36 said:
A good way to analyse the above problem would be to draw the Lewis structures.There is a reason it is named after G.N. Lewis!

Alright,
Based on Lewis structure, NH3 have three pair of bonding electrons and one pair of free electrons while BF3 have three pair of bonding electrons.

and then? How to determine which one is base or acid ?

So the electron configuration is something like this

So i think this might help

terryds
My teacher Told me if it has an empty orbital ->Lewis acid
Otherwise its most likely ->Lewis base

terryds
Thanks! I got it!

Last edited:

## What is the definition of a Lewis acid?

A Lewis acid is a chemical species that can accept a pair of electrons from a Lewis base to form a covalent bond.

## What is the definition of a Lewis base?

A Lewis base is a chemical species that can donate a pair of electrons to a Lewis acid to form a covalent bond.

## Is BH3 considered a Lewis acid or a Lewis base?

BH3 is considered a Lewis acid because it has an empty p orbital that can accept a pair of electrons from a Lewis base.

## Why is BH3 considered a weak Lewis acid?

BH3 is considered a weak Lewis acid because it does not have a complete octet of electrons and can only accept a limited number of electron pairs from a Lewis base.

## Can BH3 act as a base in certain reactions?

Yes, BH3 can act as a base in some reactions where it donates a pair of electrons to a Lewis acid to form a coordinate covalent bond.

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