Is the lone pair of electrons on the nitrogen atom in the ammonia molecule stereochemically inactive?

Aug 9, 2017

Nope...........

Explanation:

The ammonia molecule has a lone pair of electrons centred on the nitrogen atom, but ALL of the $3 \times N - H$ bonds are electron-precise $\sigma \text{-bonds}$ formed between $\dot{H}$ and the nitrogen atom. The remaining 2 electrons on the nitrogen atom comprise a stereochemically active lone pair.....and this lone pair also rationalizes the basicity of the ammonia molecule....

$O {H}_{2} + : N {H}_{3} r i g h t \le f t h a r p \infty n s N {H}_{4}^{+} + H {O}^{-}$

And to a first approximation ELECTRONIC geometry around nitrogen is tetrahedral. But MOLECULAR geometry is pyramidal.

On the other hand, the nitrogen atom of the ammonium ion is said to be QUATERNIZED $\left(\text{ammonium} \equiv N {H}_{4}^{+}\right)$; that is the nitrogen lone pair forms a so-called $\text{coordinate covalent bond}$ or $\text{dative}$ or $\text{donative bond}$ to the protium ion.......In $\text{ammonium ion}$, ALL of the $4 \times N - H$ bonds ARE EQUIVALENT.