Question

Why are all diatomic molecules linear, regardless of the number of valence electron pairs on the atoms involved?

Short answer

All diatomic molecules are linear because they consist of only two connected atoms, allowing for only one possible shape. Regardless of the number of valence electron pairs on each atom, the linear shape remains the same, as the structure is determined by the bonding between the atoms and the repulsion forces between electron pairs, according to the Valence Shell Electron Pair Repulsion (VSEPR) theory.

Step-by-step solution

Understanding diatomic molecules

A diatomic molecule consists of two atoms bonded together. Since there are only two atoms, there is no possibility for different geometries to form. The molecule must have a linear shape, as the atoms lie directly next to each other in a straight line.

Lewis structures and molecular shape

To better visualize the electron configuration in diatomic molecules, we can use Lewis structures. These structures represent atoms and their valence electrons as symbols and dots, respectively. In diatomic molecules, a single bond (or double or triple bond) connects the two atoms, leading to a linear shape. Regardless of the number of valence electron pairs on each atom, the linear shape remains the same, as the structure is determined by the bonding between the two atoms.

Valence shell electron pair repulsion (VSEPR) theory

The VSEPR theory is used to predict the shape of a molecule based on the repulsion forces between electron pairs in the valence shell of an atom. According to this theory, electrons will arrange themselves to minimize the repulsion forces. In a diatomic molecule, there are only two atoms and one bond. Therefore, there is no possibility of varying the angles between the atoms, leading to a linear shape.

Summarizing why diatomic molecules are linear

In conclusion, all diatomic molecules are linear because they consist of two connected atoms, allowing for only one possible shape. This observation holds true regardless of the number of valence electron pairs on the individual atoms involved, as the bonding and repulsion forces between the atoms dictate the linear arrangement.