A molecule with the formula AB2 has a linear geometry. How many electron groups are on the central atom?

Key Concepts

Molecular Geometry

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. It is determined by the number of bonding pairs and lone pairs of electrons around the central atom. In the case of AB2 with linear geometry, the arrangement of atoms is such that they are positioned at 180 degrees relative to each other.

Electron Groups

Electron groups include both bonding pairs of electrons (shared between atoms) and lone pairs (non-bonding electrons) around a central atom. The total number of electron groups influences the molecular geometry, as they repel each other and arrange themselves to minimize repulsion. For a linear molecule like AB2, there are typically two electron groups around the central atom.

VSEPR Theory

Valence Shell Electron Pair Repulsion (VSEPR) theory is a model used to predict the geometry of molecules based on the repulsion between electron pairs. According to VSEPR, electron groups will arrange themselves as far apart as possible to minimize repulsion, leading to specific molecular shapes. In the case of a linear AB2 molecule, VSEPR predicts two electron groups around the central atom, resulting in a straight-line arrangement.