Cambridge IGCSE Chemistry · Syllabus 0620 · Atoms, Elements and Compounds
Intermolecular forces
What is Intermolecular forces?
The weak forces of attraction that act between one molecule and the next in a simple molecular substance. They are much weaker than the covalent bonds within a molecule, so only a small amount of energy is needed to overcome them, which is why simple molecular substances have low melting and boiling points. When such a substance melts or boils, these forces are overcome while the covalent bonds inside each molecule remain intact.
This definition is part of the Atoms, Elements and Compounds chapter in Cambridge IGCSE Chemistry.
Common mistakes with Intermolecular forces
- 6. “Covalent bonds break when a molecular substance boils.” Supplement 2.5.5 Repair Only the weak forces between molecules are overcome. Steam is still made of \(\mathrm{H_2O}\) molecules, each with its covalent bonds intact. Taught fully in Lesson 2.5B. The weak intermolecular forces wording belongs to Supplement 2.5.5; at Core you describe the low melting point rather than explaining it this way.