What are VSEPR Rules?
- Identify the central atom
- Count its valence electrons
- Add one electron for each bonding atom
- Add or subtract electrons for charge
- Divide the total of these by 2 to find the total number of electron pairs
- Use this number to predict the shape
The VSEPR predicted shapes of molecules by using the number of electron pairs to determine the shape of the molecules. The shapes of the molecules can be predicted from their Lewis structures, however, with a model developed about 30 years ago, known as the valence-shell electron-pair repulsion (VSEPR) theory.
The VSEPR theory predicts that XeF₂ is linear. There are five electron regions (Steric Number = 5) about the central carbon atom. They are the three lone pairs and the two Xe-F bonds.
The lone pairs take up the most space, so they occupy the equatorial positions. The C-F which is sigma bond occupy the axial positions. The shape of the molecule refers only to the arrangement of the bonds.The bonds angles of XeF2 is 180° from each other, so XeF₂ is a linear molecule.