Lewis Dot Structure of the sulfite ion SO3-2 - Electron Dot Structure | Chemistry Net

Lewis Dot Structure of the sulfite ion SO3-2 - Electron Dot Structure

Lewis Dot Structure of the sulfite ion SO3-2 - Electron Dot>

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.

Fig. 1 : Connect the atoms of the sulfite ion (SO3-2) with single bonds.


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  .


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






  1. G.N. Lewis, J.A.C.S, 38, 762-785, (1916)
  2.  E. C. McGoran, J. Chem. Educ., 68, 19-23 (1991)
  3. A.B.P. Lever, J. Chem. Educ., 49, 819-821, (1972)

Key Terms

Lewis structures, electron dot structures, Lewis structures of the sulfite ion SO3-2, electron dot structures of the sulfite ion SO3-2, method for drawing Lewis structures,, chemistry, Chemistry Net

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