Why do ammonia and ammonium have different bonding angles even though their molecular geometry is tetrahedral
Ammonia (NH3) has a bond angle of approximately 107 degrees, while ammonium (NH4+) has a bond angle of approximately 109.5 degrees.
The difference in bond angles can be attributed to the presence of the extra hydrogen atom in ammonium. In ammonia, there are three bonded electron pairs and one lone pair around the central nitrogen atom. The lone pair occupies more space compared to bonded pairs, leading to greater repulsion between electron pairs and a slightly smaller bond angle.
In ammonium, on the other hand, there are four bonded electron pairs around the central nitrogen atom with no lone pairs. The repulsion between the bonded pairs is more symmetrical, resulting in a bond angle that closely approximates the ideal tetrahedral angle of 109.5 degrees.