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9701 A Level Chemistry/ Topic 29 Organic chemistry (A Level introduction)/ 5 interactive simulations/ drag to rotate 3D scenes

Organic chemistry (A Level introduction), made interactive

Five simulations covering Topic 29: a 3D gallery of the eight functional groups you meet at A Level, a benzene ring where you place two substituents and the compound is named with its locants, benzene in 3D as the Kekulé structure and as a delocalised ring with its p orbitals merging into a doughnut, a chiral centre beside its mirror image that you try to superimpose, and a card drill that sorts reactions into electrophilic substitution, addition-elimination, hydrolysis, reduction and oxidation.

1. Eight groups to recognise 3D · 29.1

At A Level the list of functional groups grows. Each one is a small cluster of atoms that decides how the molecule behaves, so spotting it is the first step in every question. Pick a group and it is picked out in gold on a small example molecule.

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Functional group

GROUP
Exam point: name the group, not just the molecule. An arene is the ring itself; a halogenoarene, phenol and phenylamine have an atom or group joined directly to the ring carbon, which changes their behaviour from the aliphatic version.

2. Locants on the ring 2D · 29.1

When a benzene ring carries two groups, the name must say where they are. Number the ring from one substituent: the other sits at position 2 (next door, ortho), 3 (meta) or 4 (opposite, para). Choose a substituent, click the ring, and the sim names what you built.

Substituent to place

Or try an example

NAME
RELATIVE POSITION
Naming rule: if the ring carries -COOH, -OH or -NH₂ that group defines the parent (benzoic acid, phenol, phenylamine) and takes position 1. Otherwise the ring is benzene and the prefixes are listed alphabetically, with the lowest numbers: 1,2- or 1,3- or 1,4-.

3. Benzene in 3D 3D · 29.2

Kekulé drew benzene with three C=C bonds and three C-C bonds. Measurements say otherwise: all six bonds are the same length and the ring does not behave like an alkene. Switch to the delocalised model and merge the six p orbitals into a doughnut of electron density above and below the ring.

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Model

Test with bromine water

Evidence against Kekulé: all C-C bonds 0.139 nm (between 0.154 for C-C and 0.134 for C=C), a planar ring, no decolourising of bromine water, and a hydrogenation enthalpy of −208 kJ mol⁻¹ instead of the −360 predicted. The 152 kJ mol⁻¹ difference is the extra stability from delocalisation.

4. Chirality in 3D 3D · 29.3

A carbon bonded to four different groups can be built in two ways that are mirror images and cannot be turned into each other. Those two forms are enantiomers. Pick a molecule, then try to lay the mirror image on top of the original. Finally swap one group so two of them match and watch the handedness vanish.

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Molecule

CHIRAL CENTRES
STEREOISOMERS
GROUPS THAT LINE UP
SUPERIMPOSABLE?
A chiral centre has four different groups. With n chiral centres there are up to 2n stereoisomers. Enantiomers have identical melting points and reactions but rotate plane-polarised light in opposite directions; an equal mixture of the two, a racemic mixture, does not rotate it at all.

5. Reaction types 2D · 29.4

Most exam marks for a reaction mechanism come from naming the type correctly. Each card shows an equation and its conditions. Decide which of the five types it is; the sim tells you what gave it away.

What type of reaction is it?

SCORE
STREAK
Clues: an electrophile attacking the ring with H replaced is electrophilic substitution; an acyl chloride joined to an -OH or -NH group is addition-elimination, with HCl lost; water splitting a molecule is hydrolysis; gaining H (or losing O) is reduction; gaining O (or losing H) is oxidation.
TheLucidSTEM · Cambridge International A Level Chemistry 9701 · Topic 29 Organic chemistry (A Level introduction). Every scene runs in the browser; drag to rotate 3D scenes, wheel to zoom. Values are standard textbook data rounded for teaching.

About this lab: Organic chemistry (A Level introduction)

Five interactive simulations for Cambridge A Level Chemistry 9701 topic 29 Organic chemistry: eight A Level functional groups highlighted on small 3D molecules, a benzene ring where two substituents are placed and the compound named with 1,2- 1,3- or 1,4- locants, benzene in 3D as the Kekulé structure and as six overlapping p orbitals forming a delocalised ring with the 0.139 nm bond length and the hydrogenation enthalpy of -208 against -360 kJ per mole, a chiral centre and its mirror image that cannot be superimposed, and a reaction-type sorter for electrophilic substitution, nucleophilic addition-elimination, hydrolysis, reduction and oxidation.

Five simulations covering Topic 29: a 3D gallery of the eight functional groups you meet at A Level, a benzene ring where you place two substituents and the compound is named with its locants, benzene in 3D as the Kekulé structure and as a delocalised ring with its p orbitals merging into a doughnut, a chiral centre beside its mirror image that you try to superimpose, and a card drill that sorts reactions into electrophilic substitution, addition-elimination, hydrolysis, reduction and oxidation.

Organic chemistry (A Level introduction) is a free, browser-based simulation for Cambridge International AS & A Level Chemistry 9701 (topic 29 An introduction to A Level organic chemistry). The course is assessed in Paper 1 (Multiple Choice (AS)), Paper 2 (AS Structured), Paper 3 (Advanced Practical), Paper 4 (A Level Structured), Paper 5 (Planning, Analysis, Evaluation). Syllabus for examination in 2025-2027. There are 5 tabs, each a self-contained experiment with its own controls and live readings, and nothing to install: it runs on a laptop, tablet or classroom projector.

Syllabus coverage

Full syllabus map: A Level Chemistry 9701 topic 29.

How to use this simulation

  1. 1. Eight groups to recognise. At A Level the list of functional groups grows.
  2. 2. Locants on the ring. When a benzene ring carries two groups, the name must say where they are.
  3. 3. Benzene in 3D. Kekulé drew benzene with three C=C bonds and three C-C bonds.
  4. 4. Chirality in 3D. A carbon bonded to four different groups can be built in two ways that are mirror images and cannot be turned into each...
  5. 5. Reaction types. Most exam marks for a reaction mechanism come from naming the type correctly.
  6. The buttons at the end of the tab strip give the scene the whole window (Full screen, Hide controls) and, on a dark stage, a projector-friendly palette (Light scene). Many scenes also have drag handles: drag them to change the set-up directly.

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