How does resonance describe the electron distribution in a semiquinone radical ion?

In the context of radical chemistry, the semiquinone radical ion demonstrates how resonance stabilizes a molecule through the delocalization of electrons.

When representing a semiquinone radical ion, one oxygen atom is typically depicted with a negative charge while the other holds an odd electron. However, this assignment is arbitrary, as the molecule can be equally represented by interchanging the charge and the odd electron between the two oxygen atoms.

Because the actual electron distribution is not limited to either of these individual structures, the molecule exists in an intermediate state. This phenomenon is known as delocalization or resonance. According to quantum mechanics, this resonance significantly increases the stability of the radical ion and enhances the probability of its existence.1