Question

draw a lewis structure for so₂ in which all atoms obey the octet rule. show formal charges. do not consider ringed structures.
draw a lewis structure for so₂ in which all atoms have a formal charge of zero. do not consider ringed structures.

Explanation:

To draw the Lewis structure for \(SO_2\) where all atoms obey the octet rule:

• Sulfur (\(S\)) has \(6\) valence electrons and oxygen (\(O\)) has \(6\) valence electrons. Total valence electrons \(=6 + 2\times6=18\).
• Place \(S\) in the center. Connect \(S\) to two \(O\) atoms with single bonds (\(S - O\)). Each single bond uses \(2\) electrons. So far, \(4\) electrons are used.
• Distribute the remaining \(14\) electrons as lone pairs. Each \(O\) atom gets \(6\) lone - pair electrons (to complete its octet). But then \(S\) has only \(4\) electrons. So, one of the \(O\) atoms forms a double bond (\(S=O\)).
• Calculate formal charges: Formal charge \(=V - N-\frac{B}{2}\), where \(V\) is the number of valence electrons in the free atom, \(N\) is the number of non - bonding electrons, and \(B\) is the number of bonding electrons.
• For the \(S\) atom: \(V = 6\), \(N = 2\), \(B = 6\). Formal charge \(=6 - 2-\frac{6}{2}=+1\).
• For the double - bonded \(O\) atom: \(V = 6\), \(N = 4\), \(B = 4\). Formal charge \(=6 - 4-\frac{4}{2}=0\).
• For the single - bonded \(O\) atom: \(V = 6\), \(N = 6\), \(B = 2\). Formal charge \(=6 - 6-\frac{2}{2}=-1\).

To draw the Lewis structure for \(SO_2\) where all atoms have a formal charge of zero:

• \(S\) forms a double bond with each \(O\) atom (\(S = O\)).
• Calculate formal charges:
• For \(S\): \(V = 6\), \(N = 0\), \(B = 8\). Formal charge \(=6 - 0-\frac{8}{2}=0\).
• For each \(O\): \(V = 6\), \(N = 4\), \(B = 4\). Formal charge \(=6 - 4-\frac{4}{2}=0\).

Answer:

1. Lewis structure with octet rule (showing formal charges):

• \(\overset{+1}{S}=\overset{0}{O}-\overset{-1}{O}\) (with appropriate lone pairs on \(O\) atoms).

1. Lewis structure with formal charge zero:

• \(\overset{0}{S}=\overset{0}{O}=\overset{0}{O}\) (with appropriate lone pairs on \(O\) atoms).