To calculate the formal charge on the nitrogen atom in the ammonium ion NH4+ , we can use the following formula:Formal charge = Valence electrons of the atom - Non-bonding electrons - 1/2 Bonding electrons For nitrogen, the number of valence electrons is 5. In the ammonium ion, nitrogen forms 4 single bonds with 4 hydrogen atoms, which means it has 4 bonding electrons and no non-bonding electrons.Now, we can plug these values into the formula:Formal charge = 5 - 0 - 1/2 4 Formal charge = 5 - 0 - 2Formal charge = 3So, the formal charge on the nitrogen atom in the ammonium ion NH4+ is +1.