Resonance hybrid

Definition

A resonance hybrid is a molecule or ion that is best represented by two or more valid Lewis structures, called resonance structures. The actual structure is a weighted average of these resonance forms, resulting in delocalized electrons.

5 Must Know Facts For Your Next Test

1. Resonance hybrids are depicted with a double-headed arrow between the contributing resonance structures.
2. The real structure of the molecule is more stable than any individual resonance form.
3. Resonance hybrids help to explain properties such as bond lengths and energies that cannot be described by a single Lewis structure.
4. Formal charges are used to determine the most significant resonance contributors.
5. The concept of resonance does not imply that molecules oscillate between different forms; rather, they exist as an average.

Review Questions

• What symbol is used to denote resonance between two structures?
• How does a resonance hybrid contribute to the stability of a molecule?
• Why are formal charges important when determining significant resonance contributors?

Related terms

Formal Charge:

A theoretical charge on an atom in a molecule, calculated based on the assumption that electrons in all chemical bonds are shared equally between atoms.

Delocalized Electrons:

Electrons in a molecule that are not associated with a single atom or bond but are spread over several adjacent atoms.

Lewis Structure:

A diagrammatic method for representing the valence electrons of atoms within a molecule, showing how they form covalent bonds.