SO3 2- Molecular Geometry / Shape and Bond Angles

A quick explanation of the molecular geometry of SO3 2- (Sulfite ion) including a description of the SO3 2- bond angles.

Looking at the SO3 2- Lewis structure we can see that there are thre atoms attached to the central Sulfur (S) and that there is one lone pair of electrons (on the central Sulfur).  Based on VSEPR Theory (Valence Shell Electron Pair Repulsion Theory) the electron clouds around these atoms will repel each other.  As a result they will be pushed apart giving the SO3 2- molecule a trigonal pyramidal molecular geometry or shape.

For help drawing the SO3 2- Lewis Structure see:
SO3 2- Lewis Structure - How to Draw ...

The SO3 2- bond angle will be about 106.0 degrees since it has a trigonal pyramidal molecular geometry.

--How to Determine the Molecular Geometry--

1) Draw the Lewis Structure for the compound.
2) Predict how the atoms and lone pairs will spread out when the repel each other.
3) Use a chart based on steric number (like the one in the video) or use the AXN notation to find the molecular shape. This will be determined by the number of atoms and lone pairs attached to the central atom.

Helpful Resources:
• How to Draw Lewis Structures: How to Draw Lewis Structures: Five Ea...
• Molecular Geometry and VSEPR Explained: Molecular Geometry: Rules, Examples, ...
• Molecular Geo App: https://phet.colorado.edu/sims/html/m...

Get more chemistry help at http://www.breslyn.org

Drawing/writing done in InkScape. Screen capture done with Camtasia Studio 4.0. Done on a Dell Dimension laptop computer with a Wacom digital tablet (Bamboo).

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