Cambridge IGCSE Chemistry · Syllabus 0620 · Atoms, Elements and Compounds
Delocalised electron
What is Delocalised electron?
An electron that is not held in a bond between two particular atoms and is free to move through the structure. In graphite each carbon atom is bonded to only three others, so one of its outer electrons is delocalised and can move through the layers, which is why graphite conducts electricity and can be used as an electrode. Extended candidates meet delocalised electrons again in metallic bonding, which is Supplement 2.7.1.
This definition is part of the Atoms, Elements and Compounds chapter in Cambridge IGCSE Chemistry.
Common mistakes with Delocalised electron
- 8. “Anything with a lattice structure conducts electricity.” Core 2.4.4 Repair Conduction needs a mobile charged particle. An ionic lattice has ions that are fixed until it is molten or dissolved, which is why an ionic compound conducts only in those two states. Diamond has neither ions nor delocalised electrons, so it does not conduct at all. The ionic half is taught fully in Lesson 2.4C. Supplement — Extended candidates Supplement 2.7.2 The metallic case completes the set: a metallic lattice has mobile delocalised electrons, so a metal conducts even as a solid. Taught fully in Lesson 2.7.