1. Lone pair-lone pair repulsion is strongest: Lone pairs, being closer to the central atom, experience the strongest repulsion. This is because they are not shared with another atom and are attracted more strongly to the nucleus.
2. Lone pair-bonding pair repulsion is intermediate: Lone pairs repel bonding pairs more strongly than bonding pairs repel each other. This is because the lone pair electron density is concentrated closer to the central atom, while the bonding pair electrons are spread out between two atoms.
3. Bonding pair-bonding pair repulsion is weakest: Bonding pairs, being shared between two atoms, experience the weakest repulsion. This is because the electron density is spread out over a larger region.
Consequences of Electron Pair Repulsion:
* Molecular Shape: The repulsion between electron pairs forces the molecule to adopt a specific shape that minimizes these repulsions. For example, in methane (CH4), the four bonding pairs repel each other equally, resulting in a tetrahedral shape.
* Bond Angles: The angles between bonds are also affected by the strength of the repulsion between electron pairs. For example, in water (H2O), the two lone pairs on the oxygen atom repel the two bonding pairs, compressing the H-O-H bond angle to 104.5 degrees.
* Hybridization: In some cases, the repulsion between electron pairs can lead to the hybridization of atomic orbitals, where orbitals of different shapes and energies mix to form new hybrid orbitals that are more stable.
In summary: Electron pairs in VSEPR theory behave like charged objects, repelling each other to minimize their interactions. The relative strength of these repulsions determines the shape of the molecule and the angles between its bonds.
