Using VSEPR theory, determine the electron-group geometry and molecular shape of the substances shown.
BF3: Electron Geometry: trigonal planar → Molecular Shape: trigonal planar
NF3: Electron Geometry: trigonal pyramidal 9 Molecular Shape: trigonal planaro
CF4: Electron Geometry: tetrahedral CF2H2: Electron Geometry: trigonal planar
Molecular Shape: Molecular Shape: tetrahedral trigonal planar
The Correct Answer and Explanation is :
Let’s go over the VSEPR theory and apply it to determine the electron-group geometry and molecular shape for the compounds you mentioned.
1. BF₃ (Boron Trifluoride)
- Electron Geometry: The central atom is boron, which is bonded to three fluorine atoms. There are no lone pairs on boron, so the electron groups are all bonding pairs. According to VSEPR theory, three bonding pairs around the central atom lead to a trigonal planar electron geometry.
- Molecular Shape: Since all the electron groups are bonding pairs and there are no lone pairs on the central atom, the molecular shape is also trigonal planar.
2. NF₃ (Nitrogen Trifluoride)
- Electron Geometry: The central nitrogen atom has three bonding pairs and one lone pair. In this case, the electron groups around the nitrogen form a tetrahedral electron geometry (four electron groups: three bonds and one lone pair).
- Molecular Shape: The presence of the lone pair of electrons results in a trigonal pyramidal molecular shape, as the lone pair will push the bonding pairs downward.
3. CF₄ (Carbon Tetrafluoride)
- Electron Geometry: The central carbon atom has four fluorine atoms bonded to it, with no lone pairs. This leads to a tetrahedral electron geometry.
- Molecular Shape: Since all electron groups are bonding pairs, the molecular shape is also tetrahedral.
4. CF₂H₂ (Difluoromethane)
- Electron Geometry: The central carbon atom has two fluorine atoms, two hydrogen atoms, and no lone pairs. This results in a tetrahedral electron geometry.
- Molecular Shape: Since there are only bonding pairs, the molecular shape remains tetrahedral.
Summary:
- BF₃: Electron Geometry: trigonal planar, Molecular Shape: trigonal planar
- NF₃: Electron Geometry: tetrahedral, Molecular Shape: trigonal pyramidal
- CF₄: Electron Geometry: tetrahedral, Molecular Shape: tetrahedral
- CF₂H₂: Electron Geometry: tetrahedral, Molecular Shape: tetrahedral
Now, I’ll generate an image to represent these geometries.
Here is an illustration that shows the electron-group geometries and molecular shapes for the four compounds you mentioned: BF₃, NF₃, CF₄, and CF₂H₂. The image visualizes each molecule with their corresponding geometries. Let me know if you need further clarification!
