An explanation of the molecular geometry for the HI (Hydrogen iodide) including a description of the HBr bond angles. The electron geometry for the Hydrogen iodide is also provided.

The ideal bond angle for the Hydrogen iodide is 180° since it has a Linear molecular geometry. Experimentally we would expect the bond angle to be approximately 180°.

To determine the molecular geometry, or shape for a compound like HI, 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 HI we would expect it to be Linear.

Helpful Resources:

• How to Draw Lewis Structures: https://youtu.be/1ZlnzyHahvo
• Molecular Geometry and VSEPR Explained: https://youtu.be/Moj85zwdULg
• Molecular Geo App: https://phet.colorado.edu/sims/html/molecule-shapes/latest/molecule-shapes_en.html
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).