Covalent Bonding | GCSE Chemistry

Bonding

Lesson overview

This lesson introduces the core chemistry idea, the useful equipment and the calculation or data skills used on this page.

Focussimple covalent molecules and polymers

Time45-60 minutes

EquipmentPeriodic table, calculator and notebook.

Practical linkmolecular models support explanation questions

Maths tagsformulae and displayed structure interpretation

What you will learn

Describe the key chemistry ideas behind covalent bonding and simple molecular substances.
Use precise GCSE command-word language in explanations.
Apply the idea to unfamiliar substances, data or practical contexts.
Check answers using units, state symbols, observations or balanced equations where relevant.

Core knowledge

Covalent bonding happens when non-metal atoms share pairs of electrons.
A single covalent bond is one shared pair; a double bond is two shared pairs.
Simple molecules have strong covalent bonds within molecules but weak intermolecular forces between molecules.
Simple molecular substances usually have low melting and boiling points.
Most simple covalent substances do not conduct because they have no mobile charged particles.

Covalent bonding infographic

Illustrated GCSE Chemistry infographic showing covalent dot-and-cross diagrams, shared electron pairs, simple molecules, intermolecular forces and conductivity. — Use this infographic to connect shared electron pairs, simple molecular structures, intermolecular forces, melting and boiling points, and conductivity.Download visual

Covalent Bonding practice set

Use the worked examples and practice questions on this page as a complete study task: learn the shared pair and molecule meanings, summarise the infographic in your own words, then answer the questions using the data, equations and observations given here. Check every answer for formulae and displayed structure interpretation.

Clear explanation

Covalent bonding and simple molecular substances is built around simple covalent molecules and polymers. Start by learning what shared pair and molecule mean, then connect them to the sequence in the infographic.

The key GCSE skill is to move from evidence to explanation: name the observation, data trend, particle model, structure or reaction, then explain why it supports the conclusion.

For calculation or data work, show formulae and displayed structure interpretation. For written explanations, include the specific chemistry reason rather than a memorised topic sentence.

Worked examples

Core example: hydrogen chloride

Hydrogen needs one more electron.

Chlorine has seven outer electrons and needs one more.

They share one pair.

Answer: H-Cl contains one single covalent bond.

Extension example: chlorine boiling point

Chlorine exists as Cl2 molecules.

Boiling does not break the covalent bond inside Cl2.

Only weak intermolecular forces are overcome.

Answer: Chlorine has a low boiling point because little energy is needed to overcome intermolecular forces.

Quick checks

Choose an answer, then check your thinking.

1. What is a covalent bond?

Transferred proton Lattice of positive ions Shared pair of electrons

2. Why do simple molecules usually not conduct?

No mobile charged particles They are all solids They contain ions

Practice questions

Question 1

State which atoms usually form covalent bonds.

Reveal answer and marking guidance

Answer: Non-metal atoms with other non-metal atoms.

Marking: Credit non-metals.

Question 2

Explain why methane has a low boiling point.

Reveal answer and marking guidance

Answer: Methane has simple molecules with weak intermolecular forces between molecules.

Marking: Credit simple molecules and weak intermolecular forces.

Question 3

Describe the bonding in oxygen, O2.

Reveal answer and marking guidance

Answer: Two oxygen atoms share two pairs of electrons, forming a double covalent bond.

Marking: Credit two shared pairs/double bond.

Question 4

Why does graphite conduct but simple molecules usually do not?

Reveal answer and marking guidance

Answer: Graphite has delocalised electrons that can move; simple molecules do not.

Marking: Credit delocalised electrons and no mobile charged particles in simple molecules.

Practice ladder

FluencyRecall the key definition, symbol, structure, equation or observation.

ApplicationApply covalent bonding and simple molecular substances to unfamiliar substances, practicals or data.

Practical interpretationUse evidence, method quality, uncertainty or conclusion wording where asked to evaluate.

Maths skillUse units, ratios, graphs and significant figures accurately.

Answers and marking guidance

The exact practice answers are hidden under each question so you can try first. Marks come from using the correct chemistry model, choosing the right equation where needed, keeping units with values, and explaining changes with precise words such as particles, ions, bonds, energy, rate, evidence and uncertainty.

Common mistakes

Saying covalent bonds are weak.
Forgetting a double bond has two shared pairs.
Using ionic charge language for molecules.
Saying simple molecules conduct because they contain electrons.

Extension challenge

Create a six-line revision card for covalent bonding and simple molecular substances: two definitions, one infographic detail or equation line, one equation or data check, one common mistake, and one complete explanation sentence using shared pair, molecule, intermolecular force.

Reveal answer

Example answer: A complete response names the chemistry model, uses accurate units or observations, and explains why the evidence supports the conclusion.