Secondary Chemistry Study notes
Bonding and Structure
Why salt, candle wax and copper behave differently: the particles, attractions and moving charges behind their properties.
O-Level 2026 SEC G3 2027. Extensions are labelled Pure only.
Choose a topic
6 topicsParticles and substances
Distinguish atoms, molecules and ions, then classify elements, compounds and mixtures.
Ionic bonding and properties
Follow electron transfer, build the idea of a lattice, and explain when ions can carry charge.
Covalent bonding and molecules
Read shared electron pairs and distinguish bonds within molecules from attractions between them.
Large molecules and giant structures
Compare polymer chains, diamond, graphite and silicon dioxide through their structures.
Pure onlyMetals and alloys
Recognize metals and alloys and connect their properties to their arrangement.
Work backwards from the evidence
Use melting point and conductivity together to identify and explain a likely structure.
Scope and references
Your syllabus, covered
These notes cover Chemical Bonding and Structure (topic 3) for Pure Chemistry. Explanations, examples and diagrams are original, checked against the official learning outcomes below.
- 2026 O-Level Pure Chemistry 6092 PDF
Topic 3, pages 12-13. All 17 lettered outcomes are mapped to these notes.
- 2027 SEC G3 Pure Chemistry K324 PDF
Topic 3 has the same content outcomes as the 2026 Pure syllabus.
See how the learning outcomes map to these notes
3.1(a) Form ions by electron transfer
- Electron loss produces a positive ion; electron gain produces a negative ion
- Usual noble-gas electron arrangements and unchanged nuclei
3.1(b) Represent ionic bond formation
- Metal and non-metal examples NaCl and MgCl2
- Dot-and-cross electron accounting, ion charges and formula ratios
3.1(c) Describe a giant ionic lattice
- NaCl as an extended arrangement of oppositely charged ions
- Electrostatic attractions throughout the lattice; lattice drawings are not required
3.1(d) Explain ionic physical properties
- Strong lattice attractions and high melting points
- Fixed ions in a solid; mobile ions when molten or dissolved
3.2(a) Explain a covalent bond
- A shared electron pair
- Usual full outer shells, including the two-electron first shell
3.2(b) Draw the named covalent molecules
- Dot-and-cross diagrams for H2, O2, H2O, CH4 and CO2
- Shared pairs and lone pairs
3.2(c) Deduce another molecule from its electrons
- Count valence electrons, place bonds and check outer shells
- Apply the method to an unfamiliar simple molecule
3.2(d) Connect covalent structure and properties
- Distinguish covalent bonds from intermolecular attractions
- Melting, boiling and electrical conductivity from the actual particles and structure
3.3(a) Describe metallic bonding
- Positive metal ions and delocalised electrons
- Attraction between the ions and the electron sea
3.3(b) Explain the general properties of metals
- High melting and boiling points, with appropriate exceptions
- Malleability and conduction of heat and electricity
3.4(a) Distinguish an element, compound and mixture
- Particle identity and chemical combination
- A molecular element is still an element; a compound need not consist of molecules
3.4(b) Recognise an alloy
- A mixture containing a metal and another element
- Brass and stainless steel
3.4(c) Identify metals and alloys in diagrams
- A regular arrangement in a pure metal
- Different particles in an alloy representation
3.4(d) Explain changed properties of alloys
- Different-sized particles disrupt regular layers
- Relate harder layer movement to strength or hardness
3.4(e) Compare molecular and giant structures
- Simple molecular methane and iodine
- Macromolecular poly(ethene)
- Giant covalent silicon dioxide, diamond and graphite
Strong bonds inside; weaker attractions betweenA long molecule is different from a giant network
3.4(f) Compare diamond and graphite
- Bonding, structure and electrical conductivity
- Cutting action and lubrication; drawing the full structures is not required
3.4(g) Reason from properties to structure and back
- Combine several physical observations rather than one clue
- Use bonding and particle identity to explain properties and avoid unsupported chemical predictions
A long molecule is different from a giant networkWork backwards from the evidence