GCSE · Chemistry · AQA · Spec 8462

Covalent bonding

From shared electrons to a structure

Follow the same bonding idea through the different ways covalent structures are represented.

  1. Atoms share electronsWhen atoms share a pair of electrons, that shared pair forms a strong covalent bond between the atoms.
  2. A line can replace a bondWhen the bonding is represented more simply, one line between atoms stands for one single covalent bond.
  3. The diagram becomes informationOnce the atoms and bonds are shown, count each type of atom to deduce the molecular formula of the molecule.

Small molecule or giant structure?

Small moleculesvsGiant covalent structures

Compare the scale of the structure without bringing in its bulk properties.

Focus

Overall structure

Small molecules

Separate small molecules

Giant covalent structures

A giant covalently bonded structure

The insight

Both use covalent bonds, but the overall scale and organisation of the bonded atoms are different.

Examples from this topic

Small molecules

H₂, Cl₂, O₂, N₂, HCl, H₂O, NH₃ and CH₄

Giant covalent structures

Diamond and silicon dioxide

Line representation

Small molecules

Lines can show the bonds within the molecule

Giant covalent structures

Lines can show bonds in part of the giant structure

Relationship matrix

Tap any cell to reveal it. Tap a column header to read one property down every item.

What it helps showWhat it cannot show perfectly
Dot-and-crosselectron-focused
Ball-and-stickatom-and-bond model
Two-dimensionalflat representation
Three-dimensionalspatial representation

Each cell hides a short answer and the reason behind it. Predict before you tap.

Representing polymers

Follow the move from one covalent bond to a repeating unit.

  1. Show the bonded atomsLines can represent the single covalent bonds between atoms in a polymer repeating unit.
  2. Mark one repeating unitA displayed polymer formula focuses on the part of the very large molecule that repeats.
  3. Attach the nThe repeating-unit formula uses n to show that the unit occurs a large number of times.

Read a molecular model

Problem

A model shows one carbon atom joined to four hydrogen atoms. Deduce the molecular formula.

Covalent bonding language

Say the idea before revealing each card.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

Follow shared electron pairs from individual bonds to molecules, polymers and giant structures.

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How this lesson was checked. This AQA GCSE Chemistry (specification 8462)lesson was published through Lightbulb Learning's human-designed editorial process — the educational standards, accuracy rules and publication checks it must pass were authored and approved by Philip Halpin. It passed subject-specific assessment, automated educational checks and technical publication verification before going live (publication checks completed 13 August 2026). Published pages are monitored, human spot-checking is ongoing across the lesson library, and anything found wrong is corrected or withdrawn. How our lessons are made and checked. Spotted a mistake? Email hello@lightbulblearning.co and we'll review it.