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A practical guide to choosing, building, using, teaching, cleaning and storing molecular model sets.
Molecular models help learners turn chemical names, formulae and diagrams into physical three-dimensional representations. They are particularly useful for exploring bonding, molecular shape, bond angles, structural isomerism, stereochemistry, functional groups, polymers and selected extended structures.
This guide explains how to select and use molecular model kits accurately, how to avoid common misconceptions, and how to organise the equipment for reliable classroom or laboratory use.
This guide was written and reviewed by Better Equipped's technical team, drawing on experience supplying molecular model sets, chemistry kits and practical science equipment to schools, colleges and laboratories throughout the UK.
Molecular models are simplified physical representations of chemical structures. Coloured atom centres identify elements, while rods, pegs, springs or other connectors show which atoms are bonded. The arrangement of the pieces can also represent aspects of molecular geometry.
Many chemical structures are three-dimensional. A formula such as CH4, H2O or CO2 identifies the atoms present, but it does not by itself show every feature of connectivity, bond order, lone-pair arrangement or shape. A model should therefore be built using suitable structural information and then compared with the formula and expected geometry.
Coloured components used to identify elements. The sockets supplied represent particular bonding arrangements selected by the manufacturer.
Pieces used to show connectivity. Depending on the system, different connectors or arrangements may represent single, double or triple bonds.
Models can help learners compare linear, bent, trigonal planar, tetrahedral, trigonal pyramidal and other arrangements.
Models can be rotated to explore orientation, symmetry, isomerism and the relationship between two-dimensional diagrams and three-dimensional structures.
A molecular model is a representation, not a miniature copy of a real molecule. Good teaching makes the model's purpose and limitations explicit.
| Model Type | Best For | Main Limitation |
|---|---|---|
| Ball-and-stick model | Connectivity, molecular geometry, bond angles and isomerism. | Atoms are often shown too small relative to the distances between their centres. |
| Space-filling model | Relative occupied space, molecular surface and steric crowding. | Bonds and internal connectivity can be harder to see. |
| Flexible organic model | Carbon chains, rings, conformations and stereochemistry. | Flexibility may overstate or understate the movement possible around particular bonds. |
| Teacher demonstration model | Whole-class explanation where visibility is important. | Larger components may be less convenient for complex structures. |
| Crystal or lattice model | Repeating ionic, metallic or giant covalent arrangements. | Must not be described as a model of a discrete molecule where no discrete molecule exists. |
Molecular models are used to connect chemical language with spatial structure. Their value is greatest when learners build, compare, rotate, explain and evaluate the representation rather than simply copy a finished model.
| Use | What It Helps Demonstrate | Examples |
|---|---|---|
| Covalent bonding | Which atoms are connected and whether the representation uses single, double or triple bonds. | Methane, ethene, ethyne and carbon dioxide. |
| Molecular shape | How bonding pairs and lone pairs influence molecular geometry and approximate bond angles. | Methane, ammonia, water and carbon dioxide. |
| Structural isomerism | How compounds can share a molecular formula but differ in connectivity. | Butane and methylpropane; ethanol and methoxymethane. |
| Stereochemistry | How atoms or groups can have the same connectivity but different spatial arrangements. | E/Z isomerism and enantiomers where appropriate. |
| Organic chemistry | Carbon skeletons, functional groups, homologous series and reaction products. | Alkanes, alkenes, alcohols, carboxylic acids and esters. |
| Polymers | How monomers react to form chains and how repeat units are represented. | Polyethene and other addition polymers. |
| Extended structures | Repeating arrangements in suitable specialist kits. | Sodium chloride lattices, diamond, graphite and selected metallic structures. |
Coloured components representing particular elements and bonding configurations. One element may require different centres for different geometries, charges or coordination numbers.
Short rods, pegs, links or springs used to show connectivity. Follow the kit instructions for the intended representation of different bond types.
Flexible pieces may be used for multiple bonds, rings, conformations or structures that require non-rigid connections.
Some sets include halogens, sulfur, phosphorus, metals, ions or centres with specialist geometries.
These identify the manufacturer's element colours, connector functions, intended geometries and compatible parts.
Labelled compartments reduce lost parts, prevent incompatible systems being mixed and speed up lesson preparation.
Many kits use common CPK-derived colour conventions, but manufacturers may use different colours or provide several versions of the same element. Always use the key supplied with the set.
| Element | Common Model Colour | Example Contexts |
|---|---|---|
| Carbon | Black or dark grey | Hydrocarbons, alcohols, carboxylic acids and other organic structures. |
| Hydrogen | White | Water, methane, ammonia and most organic compounds. |
| Oxygen | Red | Water, carbon dioxide, alcohols, acids and esters. |
| Nitrogen | Blue | Ammonia, amines, amino acids and selected ions. |
| Chlorine | Green | Chloroalkanes, hydrogen chloride and chlorine-containing structures. |
| Sulfur | Yellow | Sulfur-containing molecules and selected ions. |
| Phosphorus | Purple, violet or orange | Phosphorus compounds and selected biological structures. |
| Other elements | Manufacturer dependent | Check the supplied key for fluorine, bromine, iodine, metals and specialist atom centres. |
The most suitable kit depends on the scientific concept, class size, visibility required and complexity of the intended structures. Choose by learning objective rather than by the number of pieces alone.
| Model Set Type | Best For | Check Before Buying |
|---|---|---|
| Student molecular model set | Individual or small-group activities. | Number of complete working groups, replacement parts, age guidance and storage. |
| Teacher demonstration set | Front-of-class explanations and whole-room visibility. | Atom size, connector strength, display stand compatibility and ease of assembly. |
| Organic chemistry set | Hydrocarbons, functional groups, isomers, mechanisms and stereochemistry. | Availability of carbon geometries, multiple-bond connectors, rings and stereochemical centres. |
| Molecular-shape set | Electron-pair arrangements, VSEPR and bond angles. | Whether lone pairs or electron domains can be represented clearly. |
| Inorganic or coordination set | Selected ions, coordination compounds and advanced geometries. | Required coordination numbers, ligand connectors and specialist centres. |
| Crystal or lattice model | Ionic, metallic and giant covalent structures. | Whether the kit demonstrates repeating structure, coordination and unit-cell relationships accurately enough for the intended level. |
Methane is a useful introductory example because its formula and structure are unambiguous at this level: one carbon atom forms four single covalent bonds to four hydrogen atoms. The four bonding regions repel to produce a tetrahedral arrangement.
For simple molecules and ions, shape can be predicted by considering regions of electron density around the central atom. These regions repel and adopt an arrangement that reduces repulsion. Lone pairs usually repel more strongly than bonding pairs and can reduce bond angles.
| Example | Electron-Region Summary | Molecular Shape | Approximate Bond Angle | Model-Building Note |
|---|---|---|---|---|
| CO2 | Two bonding regions around carbon | Linear | 180° | Use two double-bond representations where the kit supports them. |
| BF3 | Three bonding regions around boron | Trigonal planar | 120° | All three fluorine atoms lie in one plane. |
| CH4 | Four bonding regions around carbon | Tetrahedral | 109.5° | Use a tetrahedral carbon centre. |
| NH3 | Three bonding regions and one lone pair | Trigonal pyramidal | About 107° | The lone pair may need a separate marker or label because many kits omit it. |
| H2O | Two bonding regions and two lone pairs | Bent | About 104.5° | Do not arrange the hydrogen atoms linearly. |
Use oxygen as the central atom with two O–H bonds. Include or label two lone pairs if the kit permits. The molecule is bent, not linear.
Place carbon between two oxygen atoms. Represent two C=O double bonds using the kit's intended method. The molecule is linear.
Use nitrogen as the central atom with three N–H bonds and one lone pair. The molecular shape is trigonal pyramidal.
Build a C=C double bond with each carbon bonded to two hydrogens. Compare rotation about a single bond with the restricted arrangement around the double bond.
Build both structures to show that a molecular formula can correspond to different connectivities.
Compare ethene with the polymer repeat unit. Make clear that the double-bond arrangement of the monomer is not retained in the addition-polymer chain.
Molecular models are most effective when learners move repeatedly between names, formulae, two-dimensional representations, physical models and verbal explanations.
Place the molecular formula, displayed formula, skeletal formula and model side by side. Ask what each representation includes and omits.
Ask learners to predict connectivity, shape or isomer count before they assemble the pieces.
Rotate the model, then ask learners to sketch it from a different viewpoint or translate it into another chemical representation.
Require learners to justify each bond, atom count, lone pair and shape rather than relying only on which sockets happen to fit.
Build structures with the same molecular formula and identify the precise change in connectivity or spatial arrangement.
End the activity by identifying one useful feature and one limitation of the physical representation.
Connect models to covalent bonding and common bonding patterns while avoiding the idea that socket number is a universal rule for an element.
Compare electron regions, lone pairs, shape names and approximate bond angles.
Build compounds with the same molecular formula but different atom connectivity.
Explore E/Z arrangements, chiral centres and non-superimposable mirror images using an appropriate advanced set.
Identify alcohol, carboxylic acid, ester, amine and other groups within larger structures.
Compare monomers with repeat units and show how a chain continues beyond the small section represented.
Not every chemical formula describes a discrete molecule. The terminology used with the model should match the type of substance represented.
A defined group of covalently bonded atoms, such as H2O, CO2 or CH4.
The simplest whole-number ratio of ions in an ionic compound. NaCl does not mean that solid sodium chloride consists of separate NaCl molecules.
A repeating ionic, metallic or giant covalent arrangement, such as a sodium chloride lattice, diamond or graphite.
Choose kits and supporting resources that match the learning objective, group size and storage system.
Useful for simple molecules, organic structures, isomers and chemistry demonstrations.
View Molecular ModelsDesigned for hydrocarbons, functional groups, stereochemistry and related organic structures.
View Organic SetsCompact sets suitable for individual or small-group activities and repeated hands-on practice.
View Student KitsConsider compartmented trays, parts-count sheets, colour keys, formula cards, mini whiteboards and a visualiser for whole-class discussion.
| Mistake | Why It Matters | How to Avoid It |
|---|---|---|
| Using only the molecular formula | A formula may correspond to more than one structure and may not show connectivity or bond order. | Provide a name and suitable structural representation before building. |
| Forcing pieces together | Can crack sockets, bend connectors or make parts permanently loose. | Check compatibility and alignment; use only the intended connector type. |
| Treating socket number as a universal valency rule | Elements can have different bonding states, charges and coordination environments. | Link the model to the specific chemical structure, not only to the available holes. |
| Ignoring lone pairs | Can produce an incorrect explanation of shape and bond angle. | Mark or label lone pairs even when the kit does not include visible pieces for them. |
| Assuming model colours are real | Can reinforce a misconception about atoms and molecules. | Describe colours as a code used by the kit. |
| Calling an ionic lattice a molecule | Confuses discrete molecules with repeating ionic structures and formula units. | Use correct terms and a suitable specialist lattice model. |
| Building a flat model | Can hide the actual three-dimensional arrangement. | Use the correct geometry and rotate the finished model. |
| Mixing model systems | Parts may fit poorly or use different conventions. | Keep kits separately labelled and inventoried. |
| Showing a polymer as a short complete molecule | Can hide the repeating nature and continuing chain. | Label the repeat unit and show continuation bonds or brackets where appropriate. |
| Problem | Possible Cause | What to Do |
|---|---|---|
| Pieces are difficult to connect | Wrong connector, poor alignment, worn socket or incompatible parts. | Check the model system and instructions; do not force the connection. |
| Model falls apart | Loose connectors, worn atom centres or excessive stress in the structure. | Replace worn parts and check that the selected pieces suit the geometry. |
| Model has the right formula but the wrong structure | The learner used atom count alone and did not verify connectivity. | Compare with the name and displayed, skeletal or Lewis structure. |
| Shape looks incorrect | Lone pairs were ignored, the wrong centre was used or the model was arranged flat. | Count electron regions, select the correct geometry and compare with the expected angle. |
| Students confuse atom colours | The key is missing, inconsistent or different from another kit. | Keep the manufacturer's key visible and require learners to label the elements. |
| Parts go missing | Kits are not allocated, counted back or stored by compartment. | Number each kit, use a parts list and perform a short check before dismissal. |
| Parts become sticky or discoloured | Residue, unsuitable cleaner, heat, sunlight or material ageing. | Stop using affected pieces, consult the manufacturer and replace deteriorated parts where necessary. |
| Stage | Checks |
|---|---|
| Before Use | Confirm the learning objective, structural source, correct kit, colour key, complete parts and condition of components. |
| During Use | Build gently, keep parts contained, use correct terminology and compare the model with other representations. |
| After Use | Dismantle carefully, count parts, isolate damage and clean only by an approved method. |
| Storage | Store dry, labelled, inventoried and separated from incompatible systems, heat, direct sunlight and damaging chemicals. |
| Periodic Review | Complete a full inventory, replace worn parts and update worksheets where kit conventions or curriculum needs have changed. |
They are used to represent connectivity, molecular shape, bond angles, isomerism, stereochemistry, functional groups, polymer repeat units and selected extended structures. They should be used alongside formulae and diagrams.
Not always. A molecular formula gives the number and type of atoms but may not determine connectivity, bond order or three-dimensional arrangement. Use the compound name and an appropriate structural formula or Lewis structure.
Colours are a code used to identify elements. Black carbon, white hydrogen, red oxygen and blue nitrogen are common, but the manufacturer's key takes priority.
Methane, CH4, is a useful starting point because it clearly demonstrates four C–H bonds and a tetrahedral arrangement.
No. They are simplified representations. Atom sizes, bond lengths, bond angles, colours, lone pairs, charges, electron density and molecular movement may be simplified or omitted.
Many organic model systems can represent them, but the method varies. Follow the manufacturer's instructions rather than assuming that two or three ordinary connectors always provide the intended representation.
Only where the kit is specifically suitable. A sodium chloride lattice is an extended ionic structure, not a collection of NaCl molecules, so a specialist lattice model is usually more appropriate.
Some kits include lone-pair pieces. Where they do not, use removable labels, cards or a separate diagram and explain that lone pairs affect molecular shape even though they are not visible in the model.
Keep them dry, labelled and divided into compartments. Store the instructions and colour key with the kit, avoid mixing systems and check for missing or damaged pieces after use.
Follow the manufacturer's instructions. Use a soft dry cloth for routine dust and, only where permitted, a cloth dampened with mild soapy water. Avoid solvents, abrasives, excessive heat and storing damp parts.
Choosing a model set that matches the scientific concept can make chemistry more visual, interactive and memorable. Better Equipped supplies molecular model kits and chemistry teaching equipment for schools, colleges and laboratories throughout the UK.
View Molecular Models View Molecular Models Buying Guide Contact Us for AdviceThis guide was written and reviewed by Better Equipped's technical team, drawing on experience supplying molecular model sets, chemistry teaching resources and practical science equipment to schools, colleges, universities and laboratories throughout the UK.
Its purpose is to help teachers, technicians and students use molecular and structure models accurately while recognising the limitations of physical representations.
Last reviewed and updated: July 2026
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