Account for the difference in the shape and color of the potential maps for ammonia and the ammonium ion.

Explained below.

Explanation:

The difference between the two of them will be considered from their electrostatic potential maps.

First of all the major difference is that ammonia molecule(NH3) has a lone lone pair of electron on the N atom.

Due to the this lone pair of electron on the N - atom of ammonia, it's bond angle will be slightly lesser than that of ammonium ion.

Therefore, In the electrostatic potential map of NH3, the charge distribution will not be symmetrical for the fact that there is electron rich N atom and so the N atom will be more red than the 3 hydrogen atoms (H atoms).

Whereas, the electrostatic potential map of NH4+ (ammonium ion) will be symmetrical due to the even/symmetrical distribution of all the 4 hydrogen atoms surrounding the central Nitrogen atom.

Also, the Nitrogen atom here in ammonium ion will have a lower electron density than the Nitrogen atom that's present in ammonia molecule due to the bonding existing between the lone pair electron and the Hydrogen atom

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