AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
They are unreactive and do not easily form molecules because their atoms…
Full specification wording
Group 0: They are unreactive and do not easily form molecules because their atoms have stable arrangements of electrons.
Noble gases are unreactive because their atoms already have full outer electron shells.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 2 of 5
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Noble gases are unreactive because their atoms already have full outer electron shells. A full outer shell is a stable arrangement, so there is little energetic advantage in gaining, losing or sharing electrons. This explains why they exist as single atoms and do not easily form molecules or compounds. For example, helium has two electrons in its only shell, which is full, and neon has eight electrons in its outer shell, also full. When explaining reactivity, compare the noble gas configuration with that of a reactive element such as sodium, which has one outer electron and readily loses it. Exam answers should link stability to full outer shells and to the absence of bonding.
What earns the marks
- Noble gases are unreactive because their atoms have full outer electron shells.
- A full outer shell is a stable electron arrangement.
- Because they do not need to gain, lose or share electrons, they do not easily form molecules or compounds.
- Noble gases exist as single atoms, not as diatomic molecules.
- Helium is stable with two outer electrons; other noble gases are stable with eight.
Common mistakes and how to put them right
Saying noble gases have no electrons in their outer shell.
Put it right: The outer shell is full, not empty.
Claiming noble gases cannot react at all.
Put it right: Under extreme conditions some compounds can form, but this is not required at GCSE.
Writing that noble gases form molecules because they are gases.
Put it right: Gases can be monatomic, as noble gases are.
Exam tips
- Use the phrase 'full outer shell' rather than 'stable arrangement' alone, as it is more precise.
- When comparing reactivity, refer to the electron configuration of a reactive element to show the contrast.
- If asked why argon is used in lamps, link its unreactivity to its full outer shell.
Try the lesson
The start of the Group 0: They are unreactive and do not easily form molecules because their atoms have stable arrangements of electrons. lesson, made from checked teaching notes for this specification point.
Have a go first
Why are the noble gases described as unreactive?
Listen
Noble gases are unreactive because their atoms already have full outer electron shells. A full outer shell is a stable arrangement, so there is little energetic advantage in gaining, losing or sharing electrons. This explains why they exist as single atoms and do not easily form molecules or compounds. For example, helium has two electrons in its only shell, which is full, and neon has eight electrons in its outer shell, also full. When explaining reactivity, compare the noble gas configuration with that of a reactive element such as sodium, which has one outer electron and readily loses it. Exam answers should link stability to full outer shells and to the absence of bonding. A strong answer earns marks for these points. Noble gases are unreactive because their atoms have full outer electron shells. A full outer shell is a stable electron arrangement. Because they do not need to gain, lose or share electrons, they do not easily form molecules or compounds. Noble gases exist as single atoms, not as diatomic molecules. Exam tip: Use the phrase 'full outer shell' rather than 'stable arrangement' alone, as it is more precise.
See it
Key words
Say what each word means before you turn the card.
Electron configuration
Try answering aloud or in your head before turning the card.
Chemical stability
Try answering aloud or in your head before turning the card.
Structure of noble gases
Try answering aloud or in your head before turning the card.
See every definition
- Electron configuration
- The arrangement of electrons in an atom, such as helium having two electrons in its only shell and neon having eight in its outer shell.
- Chemical stability
- A stable arrangement of electrons, which a full outer shell provides.
- Structure of noble gases
- They exist as single atoms, not as diatomic molecules.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of Group 0: They are unreactive and do not easily form molecules because their atoms have stable arrangements of electrons.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge