Bonding & StructureDeep Dive

Understanding Intermolecular Forces

Part of Simple Molecules · GCSE GCSE Chemistry revision

This deep dive covers Understanding Intermolecular Forces within Simple Molecules for GCSE Chemistry. Revise Simple Molecules in Bonding & Structure for GCSE Chemistry with 20 exam-style questions and 21 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 3 of 11 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 3 of 11

Practice

20 questions

Recall

21 flashcards

🔬 Understanding Intermolecular Forces

The Two Types of Forces:

1. COVALENT BONDS (within molecules):
• Strong bonds between atoms sharing electrons
• Hold atoms together INSIDE the molecule
• NOT broken when melting or boiling
• The molecule stays intact as a gas

2. INTERMOLECULAR FORCES (between molecules):
• Weak attractions between DIFFERENT molecules
• Hold molecules close to each other in solid/liquid
• ARE broken when melting or boiling
• Very little energy needed to overcome them

Common Simple Molecular Substances:

Water (H₂O) — Liquid at room temp:
• Boiling point: 100°C
• Relatively high for a simple molecule
• Has stronger intermolecular forces (hydrogen bonding)
• Still much lower than ionic compounds!

Carbon dioxide (CO₂) — Gas at room temp:
• Sublimes at -78°C (goes straight from solid to gas)
• Very weak intermolecular forces
• Molecules spread apart easily

Oxygen (O₂) & Nitrogen (N₂) — Gases at room temp:
• O₂ boils at -183°C, N₂ at -196°C
• Tiny molecules with very weak intermolecular forces
• Almost no attraction between molecules

Larger molecules (e.g., wax, oils):
• Higher melting points than small molecules
• More atoms = more surface area = more intermolecular forces
• Still lower than ionic/giant covalent compounds

Key Exam Point: When explaining low melting/boiling points, ALWAYS say "weak intermolecular forces" NOT "weak covalent bonds" — the covalent bonds are strong! It's the forces BETWEEN molecules that are weak.

Keep building this topic

Read this section alongside the surrounding pages in Simple Molecules. That gives you the full topic sequence instead of a single isolated revision point.

The Tale of Two Substances How It Works: Why Simple Molecules Have Low Melting Points Simple Molecular Structures Key Definitions

Practice Questions for Simple Molecules

Which type of force holds simple molecules together as a substance?

A. Weak intermolecular forces between molecules
B. Strong ionic bonds between oppositely charged ions
C. Metallic bonds from a sea of delocalised electrons
D. Covalent bonds between separate molecules

1 markfoundation

Explain why chlorine (Cl2) has a low boiling point.

2 marksstandard

Quick Recall Flashcards

What are intermolecular forces?

Weak forces of attraction between different molecules

What does molecular formula show?

Number and type of atoms in one molecule (e.g., H₂O, CO₂, CH₄)

20 questions on Simple Molecules — practise free

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The Tale of Two Substances

How It Works: Why Simple Molecules Have Low Melting Points