Group 0 (AQA GCSE Chemistry Combined Science): Revision Notes
Group 0
What are noble gases?
The elements in Group 0 of the periodic table are called noble gases. These are special elements that behave very differently from other groups. The main noble gases you need to know are:
- Helium (He)
- Neon (Ne)
- Argon (Ar)
- Krypton (Kr)
- Xenon (Xe)
- Radon (Rn)
Noble gases are also sometimes called "inert gases" because of their extremely low chemical reactivity. They make up about 1% of Earth's atmosphere, with argon being the most abundant.
Why are noble gases unreactive?
Noble gases are unreactive (also called inert) because of their electronic structure. This means they don't easily join with other elements to make compounds.
Electronic configuration
The reason noble gases are so stable is because they have full outer electron shells:
- Helium has 2 electrons in its outer shell (which is full for the first shell)
- All other noble gases have 8 electrons in their outer shell
This complete outer shell makes the atoms very stable. They don't need to gain, lose, or share electrons with other atoms. This is why they rarely form compounds.
This electronic configuration is called the "octet rule" for most noble gases (except helium, which follows the "duet rule"). Other elements often react to try to achieve this same stable electron arrangement.
Physical properties
Boiling points
Noble gases show a clear pattern in their boiling points:
- Boiling points increase as you go down the group
- Helium has the lowest boiling point (-269°C)
- The larger the atom, the higher the boiling point
This happens because larger atoms have stronger intermolecular forces (called van der Waals forces) between them. As the electron cloud gets bigger, these weak attractive forces become stronger, requiring more energy to separate the atoms during boiling.
Compound formation
Noble gases form very few compounds because they are so unreactive. However:
Exceptions to the "no compounds" rule:
- A few compounds of the heavier noble gases (like xenon) have been made in laboratories
- These compounds are very rare and difficult to make
- Helium and neon form no known compounds at all
The compounds that do exist are usually covalent compounds where electrons are shared between atoms. The first noble gas compound ever made was xenon hexafluoroplatinate (XePtF₆) in 1962.
Key Points to Remember:
- Noble gases are Group 0 elements that are very unreactive
- They have full outer electron shells which makes them stable
- Boiling points increase down the group due to stronger intermolecular forces
- They rarely form compounds because they don't need to gain or lose electrons
- The first few noble gases are helium, neon, argon, krypton, and xenon
- Only the heaviest noble gases can form compounds under special conditions