SO2 Lewis Structure - How to Draw the Lewis Structure for SO2 (Sulfur Dioxide)

A step-by-step explanation of how to draw the SO2 Lewis Structure (Sulfur Dioxide)

Note: From an experimental view (using x-ray crystallography or something similar) we find the single and double bond (we should also take into account resonance, though).

From a theoretical perspective (using formal charges) we get two double bonds. Since most students don't have access to the experimental tools or data, the theoretically predicted structure is shown here. It's also what would be expected on exams for general chemistry courses.

For the SO2 Lewis structure we first count the valence electrons for the SO2 molecule using the periodic table. Once we know how many valence electrons there are in SO2 we can distribute them around the central atom and attempt to fill the outer shells of each atom.

There are a total of 18 valence electrons for the SO2 Lewis structure.

When we are done adding valence electrons we check each atom to see if it has an octet (full outer shell). We also need to check to make sure we only used the number of available valence electrons we calculated earlier.

For the Lewis structure for SO2 you have to take formal charges into account to find the best Lewis structure for the molecule. The first Lewis Structure for SO2 may not be what you are looking for.

Note that SO2 can have an Expanded Octet and have more than eight valence electrons. Because of this there may be several possible Lewis Structures. To arrive at the most favorable Lewis Structure we need to consider formal charges. See how to calculate formal charges:    • Formal Charges: Calculating Formal Ch...  

----Lewis Resources----
• Lewis Structures Made Simple:    • How to Draw Lewis Structures: Five Ea...  
• More practice:    • Lewis Dot Structure Practice Problems...  
• Counting Valence Electrons:    • Finding the Number of Valence Electro...  
• Calculating Formal Charge:    • Formal Charges: Calculating Formal Ch...  
• Exceptions to the Octet Rule:    • Exceptions to the Octet Rule  

---Steps to Write Lewis Structure for compounds like SO2
1. Find the total valence electrons for the SO2 molecule.
2. Put the least electronegative atom in the center. Note: Hydrogen (H) always goes outside.
3. Put two electrons between atoms to form a chemical bond.
4. Complete octets on outside atoms.
5. If central atom does not have an octet, move electrons from outer atoms to form double or triple bonds.

Lewis Structures are important to learn because they help us understand how atoms and electrons are arranged in a molecule, such as Sulfur dioxide. This can help us determine the molecular geometry, how the molecule might react with other molecules, and some of the physical properties of the molecule (like boiling point and surface tension).

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