Answer :
Final answer:
The formal charge on nitrogen in NH4+ is +1. This is determined by subtracting the 4 electrons 'owned' from bonding from the 5 valence electrons nitrogen normally has, indicating one missing electron and thus a +1 charge.
Explanation:
The student has asked about the formal charge on nitrogen in NH4+. To determine the formal charge on the nitrogen atom, we need to consider the number of valence electrons in a neutral nitrogen atom and the electrons it effectively 'owns' in the bonded structure. A neutral nitrogen atom has five valence electrons. In NH4+, nitrogen shares four bonding pairs of electrons with hydrogen atoms and effectively 'owns' one additional electron for each covalent bond plus its lone pairs. In this case, nitrogen has no lone pairs, so it 'owns' 4 electrons from the bonding pairs. Subtracting these 4 electrons from the 5 valence electrons nitrogen normally has, there is one missing electron, which results in a formal charge of +1 on the nitrogen atom. This is consistent with the charge on the NH4+ ion, as all hydrogen atoms have a formal charge of zero in the compound.
