Question

Write Lewis structures that obey the octet rule for the following species. Assign the formal charge for each central atom. a. \(\mathrm{POCl}_{3}\) e. \(\mathrm{SO}_{2} \mathrm{Cl}_{2}\) b. \(\mathrm{SO}_{4}^{2-}\) f. \(\mathrm{XeO}_{4}\) c. \(\mathrm{ClO}_{4}^{-}\) g. \(\mathrm{ClO}_{3}^{-}\) d. \(\mathrm{PO}_{4}^{3-}\) h. \(\mathrm{NO}_{4}^{3-}\)

Short answer

The short version of the answer to the question is: a) \(\mathrm{POCl}_{3}\): Lewis structure: [P](=O)(-Cl)3, Formal charge of \(P\) = 0. b) \(\mathrm{SO}_{4}^{2-}\): Lewis structure: [S](=O)4 with two resonance structures, Formal charge of \(S\) = 0. c) \(\mathrm{ClO}_{4}^{-}\): Lewis structure: [Cl](=O)4, Formal charge of \(Cl\) = 0. d) \(\mathrm{PO}_{4}^{3-}\): Lewis structure: [P](=O)4 with three resonance structures, Formal charge of \(P\) = 0. e) \(\mathrm{SO}_{2}\mathrm{Cl}_{2}\): Lewis structure: [S](=O)2(-Cl)2, Formal charge of \(S\) = 0. f) \(\mathrm{XeO}_{4}\): Lewis structure: [Xe](=O)4, Formal charge of \(Xe\) = 0. g) \(\mathrm{ClO}_{3}^{-}\): Lewis structure: [Cl](=O)3(-O), Formal charge of \(Cl\) = 0. h) \(\mathrm{NO}_{4}^{3-}\): Lewis structure: [N](=O)4, Formal charge of \(N\) = +1.

Step-by-step solution

a) \(\mathrm{POCl}_{3}\)

1. First, count the total number of valence electrons in the molecule: \(P\) has 5 valence electrons, and each \(Cl\) has 7 valence electrons. Thus, there are a total of (5 + 3*7) = 26 valence electrons. 2. Next, place the central atom (\(P\) in this case) and connect it to the surrounding atoms (\(Cl\)) with single bonds. This will use 6 of the valence electrons (2 each bond). Remaining valence electrons = 20. 3. Now, fill the octets of surrounding atoms (\(Cl\)) before filling the central atom. Each \(Cl\) needs 6 more electrons to complete its octet. All the remaining 20 electrons are used for this. 4. Finally, find the formal charge of the central atom \(P\). Formal charge = (valence electrons - non-bonding electrons - 1/2 bonding electrons). Formal charge of \(P\) is (5 - 0 - (1/2)* 6) = 0.

b) \(\mathrm{SO}_{4}^{2-}\)

1. Count the total number of valence electrons: \(S\) has 6, each \(O\) has 6, and there are 2 extra from the charge. Total valence electrons = (6 + 4*6 + 2) = 32. 2. Place the central atom (\(S\)) and connect it to the surrounding atoms (\(O\)) with single bonds, using 8 valence electrons. Remaining valence electrons = 24. 3. Fill the octets of surrounding atoms (\(O\)). Each \(O\) needs 6 more electrons to complete its octet. All of the remaining 24 electrons are used for this. 4. Calculate the formal charge of the central atom \(S\). Formal charge = (6 - 0 - (1/2)* 8) = 0.

c) \(\mathrm{ClO}_{4}^{-}\)

1. Count the total number of valence electrons: \(Cl\) has 7, and each \(O\) has 6 valence electrons, plus 1 extra from the charge. Thus, the total is (7 + 4*6 + 1) = 32 valence electrons. 2. Place the central atom (\(Cl\)) and connect it to the surrounding atoms (\(O\)) with single bonds, using 8 valence electrons. The remaining valence electrons = 24. 3. Fill the octets of surround... -*-