Resonance Structures - AP® Chemistry Definition

Reviewed by: Alexandra Brennan

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What are resonance structures?

Resonance structures refer to different Lewis structures that represent the same molecule and illustrate the delocalisation of electrons within the molecule. In AP® Chemistry, understanding resonance is crucial as it helps explain the stability and reactivity of compounds. These structures are used when a single Lewis structure cannot accurately depict the delocalised nature of electrons within a molecule. By considering all resonance structures, students can better appreciate the distribution of electron density and predict molecular properties more accurately.

Diagram showing resonance structures of a nitrate ion with electron pairs oscillating between positions, illustrating negative charge distribution.
Resonance structures of the nitrate(V) ion

It is important to note that resonance structures themselves are not real; instead, the true molecular structure is a hybrid of all possible resonance forms, leading to an overall stabilisation due to electron delocalisation.

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Alexandra Brennan

Reviewer: Alexandra Brennan

Expertise: Chemistry

Alex studied Biochemistry at Newcastle University before embarking upon a career in teaching. With nearly 10 years of teaching experience, Alex has had several roles including Chemistry/Science Teacher, Head of Science and Examiner for AQA and Edexcel. Alex’s passion for creating engaging content that enables students to succeed in exams drove her to pursue a career outside of the classroom at SME.

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