8.5 Noble gases
- Syllabus
- 0620–2026–2027
- Topic
- 8.5
- Level
- —
Learning objectives
Explain noble-gas unreactivity
The Group VIII noble gases are unreactive, monatomic gases. Monatomic means that their particles are single atoms, not bonded pairs or larger molecules.
| Noble gas | Electronic configuration | Outer shell |
|---|---|---|
| helium | 2 | first shell full with 2 electrons |
| neon | 2,8 | outer shell full with 8 electrons |
| argon | 2,8,8 | outer shell full with 8 electrons |
A full outer electron shell is already stable. Noble-gas atoms therefore have little tendency to gain, lose or share electrons, so they rarely form bonds and are very unreactive.
Do not say every noble gas has eight outer electrons: helium's only shell is full with two. Also, being a gas or monatomic does not cause inertness; the full outer shell explains it.