Oxygen, in addition to its diatomic form, also forms the homonuclear triatomic molecule, ozone (O).

In the case of a triatomic molecule, this means that the eigenvalues can intersect at a point only (see conical intersection).

We find a deviation from the two rules for triatomic molecules.

These singular atoms then regroup in clusters of three to form the triatomic molecule, ozone (O).

The cation is also the simplest triatomic molecule, since its two electrons are the only valence electrons in the system.

A linear triatomic molecule would only be considered non-polar if it is symmetric through the central atom.

The vibrational modes of a triatomic molecule can be determined in specific cases.

Ozone, O is an example of a triatomic molecule with all atoms the same.

Mercuric chloride is not a salt but a linear triatomic molecule, hence its tendency to sublime.

In this sense, the triatomic molecule (for example, water, or the carbon dioxide) can be treated as a three-body problem.