To calculate the formal charge on the nitrogen atom N in the ammonium ion NH4+ , we can use the following formula:Formal charge = Valence electrons of N - Non-bonding electrons - 1/2 * Bonding electrons Step 1: Determine the valence electrons of nitrogen N Nitrogen is in group 15 of the periodic table, so it has 5 valence electrons.Step 2: Determine the non-bonding electronsIn the ammonium ion, nitrogen is bonded to four hydrogen atoms, and there are no lone pairs non-bonding electrons on the nitrogen atom. So, the non-bonding electrons are 0.Step 3: Determine the bonding electronsEach nitrogen-hydrogen bond in the ammonium ion has 2 electrons. Since there are 4 nitrogen-hydrogen bonds, there are a total of 4 * 2 = 8 bonding electrons.Now, we can plug these values into the formula:Formal charge = 5 - 0 - 1/2 * 8 Formal charge = 5 - 0 - 4Formal charge = +1So, the formal charge on the nitrogen atom N in the ammonium ion NH4+ is +1.