Channel: Wayne Breslyn

Category: Education

Description: An explanation of the molecular geometry for the SiO4 4- (Silicate ion) including a description of the SiO4 4- bond angles. The electron geometry for the Tetrafluoroborate ion is also provided. The ideal bond angle for the Silicate ion is 109.5° since it has a Tetrahedral molecular geometry. Experimentally we would expect the bond angle to be approximately 109.5°. To determine the molecular geometry, or shape for a compound like SiO4 4- 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 SiO4 4- we would expect it to be Tetrahedral. Helpful Resources: • How to Draw Lewis Structures: youtu.be/1ZlnzyHahvo • Molecular Geometry and VSEPR Explained: youtu.be/Moj85zwdULg • Molecular Geo App: phet.colorado.edu/sims/html/molecule-shapes/latest/molecule-shapes_en.html Get more chemistry help at 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).