Group 0 (AQA GCSE Chemistry): Revision Notes
Group 0
Group 0 contains special elements known as the noble gases. These elements are found on the far right of the periodic table and have unique properties that make them very different from other elements.
What makes noble gases special
Noble gases are extremely unreactive (also called inert). This means they rarely form compounds or react with other elements. The reason for this unusual behaviour lies in their electronic structure.
Electronic structure of noble gases
The noble gases have full outer electron shells, which makes them very stable. Let's examine the electronic configurations of the first three noble gases:
Electronic Configurations of Noble Gases
- Helium has 2 electrons in its outer shell (electronic configuration: 2)
- Neon has 8 electrons in its outer shell (electronic configuration: 2,8)
- Argon has 8 electrons in its outer shell (electronic configuration: 2,8,8)
The next three noble gases are krypton, xenon, and radon. They also have 8 electrons in their outer shells, following the same pattern of complete outer electron shells.
Why noble gases are unreactive
Because noble gases have complete outer electron shells, their atoms don't need to gain, lose or share electrons. This stable electron arrangement means:
- They don't easily form molecules
- They exist as single atoms
- They are chemically inert under normal conditions
This fundamental principle explains why noble gases behave so differently from other elements in the periodic table.
Physical properties - boiling points
Noble gases show a clear pattern in their boiling points. The boiling points increase as you go down the group, with helium having the lowest boiling point.
Boiling Point Trend: The trend continues: He < Ne < Ar < Kr < Xe
This happens because larger atoms have stronger intermolecular forces between them, requiring more energy to separate them during boiling.
Recent discoveries about noble gas compounds
For many years, scientists thought noble gases could never form compounds. However, modern research has revealed some fascinating exceptions:
Timeline of Noble Gas Compound Discoveries:
- In 1933, scientists predicted that heavier noble gases might form a few compounds
- Several compounds of xenon (like XeF₄ and XeO₄) have been made in laboratories
- A few krypton compounds have been created
- The first argon compound was discovered in 2000
- No helium or neon compounds are known
These compounds can only be formed under special conditions because the atoms still prefer to stay unreactive.
Key Points to Remember:
- Noble gases are in Group 0 and are extremely unreactive due to full outer electron shells
- Helium has 2 outer electrons, all others have 8 outer electrons
- Boiling points increase down the group (He lowest, Xe highest)
- Some compounds of heavier noble gases can be made under special conditions
- They exist as single atoms, not molecules, under normal conditions