Answer
See the explanation
Work Step by Step
I. The main postulate of the VSEPR (Valence Shell Electron Pair Repulsion) model is that the arrangement of electron pairs around a central atom in a molecule or ion will adopt a geometry that minimizes the repulsive forces between these electron pairs.
The five base geometries (along with their bond angles) that most molecules or ions adopt to minimize electron-pair repulsions are:
1. Linear (180°): Two electron pairs or one bonding pair and one lone pair.
2. Trigonal planar (120°): Three electron pairs or two bonding pairs and one lone pair.
3. Tetrahedral (109.5°): Four electron pairs or four bonding pairs.
4. Trigonal bipyramidal (90° and 120°): Five electron pairs or three bonding pairs and two lone pairs.
5. Octahedral (90°): Six electron pairs or six bonding pairs.
The bond angles in actual molecules are sometimes slightly less than the predicted values by the VSEPR model due to the following reasons:
1. Lone pair-bonding pair repulsions: Lone pairs occupy more space than bonding pairs, leading to a greater repulsion and a slightly smaller bond angle.
2. Molecular distortions: Intermolecular forces, such as hydrogen bonding or dipole-dipole interactions, can cause the molecule to distort slightly from the ideal geometry predicted by the VSEPR model.
3. Hybridization effects: The VSEPR model assumes ideal hybridization, but in reality, the hybridization may not be perfect, leading to slight deviations in bond angles.
