AQA Chemistry 5.1.2.4
Group 0: the noble gases
A full outer shell explains why these gases hardly react and exist as single atoms. Bigger atoms explain the boiling-point trend, so you can predict radon’s.
Combined Science · Higher tier
Start here
Party balloons.
Party balloons that float are filled with helium. At birthday parties they are often tied up right beside the cake and its lit candles.
If you had to guess, does helium react easily, or hardly at all?
Full outer shells
Stable atoms, so unreactive and single.
The noble gases are unreactive and do not easily form molecules, because their atoms have stable arrangements of electrons. They have eight electrons in their outer shell, except helium, which has only two. So they exist as single atoms: they are monatomic. Pick an atom.
Helium: 2 electrons. Its only shell is full. No tendency to gain, lose or share electrons, so it exists as single atoms and hardly reacts.
When atoms of other elements react, they gain, lose or share electrons and end up with the electron arrangement of a noble gas. That is in the metals and non-metals and bonding lessons.
Down the group · predict each one
Boiling point rises with relative atomic mass.
Step down the group. Before each boiling point is shown, predict whether it is higher or lower than the one above. Then use the trend to predict radon’s.
Will neon’s boiling point be higher or lower than helium’s (-269 °C)?
Why it rises
Going down the group, the atoms get bigger and their relative atomic mass increases. The forces between the atoms get stronger, so more energy is needed to overcome them: the boiling point rises. Boiling separates the atoms; it does not break anything inside them. Density also increases down the group.
Think again · because they’re gases?
“Noble gases don’t react because they are gases.”
Your call
ChooseChlorine and oxygen are gases too, and both react readily. So why are the noble gases unreactive?
Sort
Same for all, changes, or not true?
Place each statement about the noble gases.
Tap a card, then tap the box it belongs in. Tap a placed card to take it back.
Command words in this lesson
- Explain
- Start from the electrons: full outer shell, so stable, so unreactive.
- Predict
- Follow the trend in the data, and say which way and roughly how much.
- Compare
- Give the property for both, with the reason.
Key fact
Noble gases are unreactive because their atoms have stable arrangements of electrons. Their boiling points increase with increasing relative atomic mass, going down the group.
Key note · AQA 5.1.2.4
Group 0: the noble gases
- Group 0 elements are the noble gases. They are unreactive and do not easily form molecules.
- Their atoms have stable arrangements of electrons: 8 in the outer shell, or 2 for helium.
- They exist as single atoms (monatomic).
- Boiling points increase with increasing relative atomic mass, going down the group.
- Bigger atoms, stronger forces between atoms, more energy needed to overcome them.
- You can predict an unknown value, such as radon’s boiling point, from the trend.
Photograph this card. Tomorrow, cover it and say each line first.
Previous and next
Connects to
Ask MrBadmus
Not sure why boiling point rises down the group?
Boiling points are rounded to the nearest degree. Atom diagrams are not to scale.