Chemical Bonding and Molecular Structure

Chemistry · Class 11

Simulation · Chemistry · Class 11

Resonance: one real structure

"Resonance: one real structure" is a free, interactive Class 11 Chemistry simulation for NEET and JEE, built on the NCERT section "Resonance structures" in Chemical Bonding and Molecular Structure. Canonical forms of O3, CO3²⁻ and NO3⁻ are overlaid into one hybrid with fractional bond orders and measured bond lengths between the single and double values; no flipping animation, a fixed hybrid. NEET has asked about this idea 1 time in 10 years of papers. JEE Main asked 47 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).

From the lesson Resonance structures in Chemical Bonding and Molecular Structure. Change the values and watch what happens.

Resonance: one real structureChemistry · Class 11

What it shows

NCERT § "Resonance Structures"

Canonical forms of O3, CO3²⁻ and NO3⁻ are overlaid into one hybrid with fractional bond orders and measured bond lengths between the single and double values; no flipping animation, a fixed hybrid.

Controls

3 to try

  • Segmentedspecies O3 / CO3²⁻ / NO3⁻ / CO2
  • Toggleshow contributing structure 1 / 2 / 3 / hybrid
  • Readoutbond order and length per bond

Try this

Predict the C–O bond order in carbonate (4/3) by choosing it on a dial; goal checks the value and shows all three bonds equal.

Common mistake

Resonance structures are real and the molecule flips between them.

In NEET

10 years of papers

Asked 1 time in 10 years of NEET.

See the past questions: Resonance and Mesomerism, Chemical Bonding and Molecular Structure (chapter)

In JEE Main

42 shifts analysed

47 questions from Chemical Bonding and Molecular Structure across the 42 JEE Main shifts Lumi has analysed (2017–2026).

See the past questions

The idea behind it

NCERT § "Resonance Structures"

  • If no one Lewis structure can describe a molecule, several structures are drawn that share the same arrangement of nuclei but place the electrons differently; the real molecule is a hybrid of them.
  • Ozone has two equal O–O bonds of 128 pm, between a single (148 pm) and a double (121 pm) O–O bond, which no single Lewis structure can show.
  • The carbonate ion has three identical C–O bonds, and CO₂ is also described by resonance.
  • The resonance hybrid has lower energy than any contributing structure, which stabilises the molecule.
  • Resonance structures do not exist separately and the molecule does not flip between them; there is no equilibrium between the canonical forms.

Questions

5 answers

What does the "Resonance: one real structure" simulation show?
Canonical forms of O3, CO3²⁻ and NO3⁻ are overlaid into one hybrid with fractional bond orders and measured bond lengths between the single and double values; no flipping animation, a fixed hybrid.
What mistake does the "Resonance: one real structure" simulation fix?
A common mistake it clears up: resonance structures are real and the molecule flips between them.
Has NEET asked about this idea?
Yes. NEET has asked about this idea 1 time in 10 years of papers.
Does JEE Main ask questions from Chemical Bonding and Molecular Structure?
Yes. JEE Main asked 47 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
Is this simulation free?
Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Resonance structures" in Chemical Bonding and Molecular Structure (Class 11 Chemistry).

Embed this simulation

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