Electron Geometry vs Molecular Geometry: Explanation & Examples

An explanation of the difference between molecular geometry and electron geometry. The primary difference is that with molecular geometry we include only the atoms in naming the geometry. It is important to remember that if there are unbonded electron pairs (lone pairs) on the central atom they still are there and affect the geometry - we just don't use them to name the geometry.

For electron geometry we include both the atoms and lone pairs when we name the geometry.

Helpful Resources:

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

To determine the molecular geometry, or shape for a compound , we complete the following steps:

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.

If you are trying to find the electron geometry for SeF6 we would expect it to be Octahedral.

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).