Lewis Dot Structure of the sulfite ion SO3-2
A simple method for writing Lewis Structures is given in a previous article entitled “Lewis Structures and the Octet Rule”.
Several worked examples relevant to this procedure were given in previous posts please see the Sitemap - Table of Contents (Lewis Electron Dot Structures).
Let us consider the case of the sulfite ion. The chemical formula is SO3-2 .
What is the SO3-2 Lewis structure?
Step 1: Connect the atoms with single bonds. The central atom is the sulfur atom.
Step 2: Calculate the # of electrons in π bonds (pi bonds, multiple bonds) using formula (1):
Where n in this case is 4 since SO3-2 consists of four atoms.
Where V = (6 + 6 + 6 + 6 ) – (-2) = 26 , V is the number of valence electrons of the ion.
Therefore, P = 6n + 2 – V = 6 * 4 + 2 – 26 = 0 There are no π electrons in SO3-2
Therefore, the structure in Step 1 is a plausible Lewis structure of SO3-2.
Electrons are placed around each atom so that the octet rule is obeyed. Since S is a third row element can accommodate more than 8 valence electrons.
Step 3 & 4: The Lewis, resonance structures of SO3-2 are as follows:
![Fig. I.2 : Lewis dot structures of SO3-2 . Fig. I.2 : Lewis dot structures of SO3-2 .](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJRI2iu2PAcYg7QJtMIeF15hgKSwEkEWnHSTiG-geafOPOTcX8ysHO6SvLvrw6pzgAcqWS00B2yUnkniV3W8BaHJYQclryQPZudUbSo2hXmQ3_UTbMfMKllKZlopgvo8nNOyTWDAlYdgw/s280/so3-2_f.png)
Resonance Structures #1-#3 are more stable due to less charge separation - even though the S atom has more than 8 electrons (expanded octet) - comparing to Structure #4. Structure #4 is less stable because of larger charge separation.
Relevant Posts - Relevant Videos
Lewis Structures|Octet Rule: A Simple Method to write Lewis Structures
Simple Procedure for writing Lewis Structures – Lewis Structures for sulfur trioxide (SO3)
Dot Structure |How do I draw a Lewis Structure for a molecule - Lewis Structure of Cyanamide
References
- G.N. Lewis, J.A.C.S, 38, 762-785, (1916)
- E. C. McGoran, J. Chem. Educ., 68, 19-23 (1991)
- A.B.P. Lever, J. Chem. Educ., 49, 819-821, (1972)
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