To calculate the formal charge of the nitrogen atom in the nitrate ion NO3- , we will use the following formula:Formal charge = Valence electrons of the atom - Non-bonding electrons - 1/2 Bonding electrons In the nitrate ion, nitrogen is bonded to three oxygen atoms through two single bonds and one double bond. Nitrogen has 5 valence electrons, and there are no non-bonding electrons on the nitrogen atom in this case.Let's count the bonding electrons:- Two single bonds to oxygen atoms: 2 2 = 4 electrons- One double bond to an oxygen atom: 2 2 = 4 electrons- Total bonding electrons: 4 + 4 = 8 electronsNow, we can calculate the formal charge of the nitrogen atom:Formal charge = 5 - 0 - 1/2 8 Formal charge = 5 - 0 - 4Formal charge = +1The formal charge of the nitrogen atom in the nitrate ion NO3- is +1.Now, let's determine if the nitrate ion is a stable or unstable species based on formal charge. The overall charge of the nitrate ion is -1, which is the sum of the formal charges of all atoms in the ion. The formal charges of the three oxygen atoms are -2, -1, and -1, respectively. When we add these formal charges to the formal charge of the nitrogen atom +1 , we get:Overall charge = +1 + -2 + -1 + -1 = -1Since the overall charge of the nitrate ion is equal to its actual charge -1 , the nitrate ion is considered a stable species. The formal charges are distributed in such a way that they minimize the overall charge and follow the octet rule, making the nitrate ion a stable and common polyatomic ion.