AQA GCSE Chemistry Foundation (8462), Foundation tier · Atomic structure and the periodic table › The periodic table
Practise Group 0. 7 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
The noble gases in Group 0: why they are unreactive, how their electrons are arranged, and the trend in boiling point down the group. Questions ask you to explain their unreactivity and to predict properties from data.
Key facts
Group 0 = noble gases: He, Ne, Ar, Kr, Xe, Rn
Unreactive: stable arrangement of electrons (full outer shell)
Outer electrons: 8, except helium which has 2
Exist as single atoms, not molecules
Boiling point increases down the group (as relative atomic mass increases)
Notes
The noble gases
The Group 0 elements are called the noble gases: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn).
They are all colourless gases at room temperature.
They are unreactive and do not easily form molecules, so they exist as single atoms.
Why they are unreactive
diagram
Their atoms have stable arrangements of electrons: a full outer shell.
The noble gases have eight electrons in their outer shell, e.g. neon is 2,8 and argon is 2,8,8.
Helium is the exception: it has only two electrons, but that is a full outer shell because its only shell is the first shell.
A full outer shell is a stable arrangement, so noble gases are unreactive.
With a full outer shell, the atoms do not need to lose, gain or share electrons, so they do not easily react.
Trend in boiling point
diagram
The boiling points of the noble gases increase going down the group, as the relative atomic mass increases.
Helium has the lowest boiling point (about −269 °C) and radon the highest (about −62 °C). All are below room temperature, so all are gases.
Boiling point increases down the group.
To predict a missing value from a table, check which way the values change and give a value that fits between its neighbours.
How to answer each type of question
Explain why the noble gases are unreactive
2 marksGrade 5
Say the atom has a full outer shell (8 electrons, or 2 for helium).
Say this is a stable arrangement, so the atom does not need to lose, gain or share electrons.
Example. Argon is used inside some light bulbs because it is unreactive. Explain why argon is unreactive. Answer in terms of electrons.
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Argon has a full outer shell / 8 electrons in its outer shell (1). This is a stable arrangement, so argon atoms do not need to lose, gain or share electrons (1).
Describe the trend and explain helium
2 to 3 marksGrade 5
Describe the trend in the direction the question asks (down the group).
For helium, say its outer shell is the first shell, which is full with 2 electrons.
Example. (a) Describe the trend in boiling point in Group 0. (b) Helium has only two electrons in its outer shell. Explain why helium is still unreactive.
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(a) Boiling point increases going down the group / as relative atomic mass increases (1). (b) Its outer shell is the first shell, which is full with 2 electrons (1), so it has a stable arrangement of electrons (1).
Don’t lose marks
Saying helium has 8 outer electrons.
Writing 'full shells' without saying which one: the key idea is a full outer shell.
Getting the boiling point trend backwards.
Saying noble gases are unreactive because they are gases.
Misreading negative temperatures: −186 °C is higher than −246 °C.
More tips
Memory tricks
Group 0 is a reminder of their almost zero reactivity.
Heavier noble gas, higher boiling point.
Helium is the odd one out: a full outer shell with only 2 electrons.
Exam technique
Use the phrase 'stable arrangement of electrons' or 'full outer shell' in explanations.
When predicting from a table, give a single value (not a range) that fits the pattern, with its unit.
Read negative numbers carefully: the value closer to zero is the higher temperature.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
Name Group 0 and some of its elementsThe noble gases: helium, neon, argon, krypton, xenon and radon.
Grade 4
State that noble gases are unreactiveThey are unreactive and do not easily form molecules; they exist as single atoms.
Grade 5
Explain their unreactivity using electronsTheir atoms have stable arrangements of electrons: a full outer shell of 8 (2 for helium).
Grade 5
Describe the boiling point trendBoiling points increase going down the group, as relative atomic mass increases.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Group 0 is the last group in the periodic table. What name is given to the elements in Group 0?
the noble gases
The elements in Group 0 are called the noble gases. Name the noble gas with the smallest atomic number.
helium
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Group 0 is the last group in the periodic table.
(a) What name is given to the elements in Group 0?[1]
(b) Explain why the elements in Group 0 are unreactive.[1]
(c) How many electrons are in the outer shell of a helium atom?[1]
(d) Which is the formula of argon gas? Tick (✓) one box.[1]
Ar
Ar2
Ar4
Ar8
Show the answer and mark scheme
(a)Answer: the noble gases
noble gases
(b)Answer: Their atoms have a stable arrangement of electrons / a full outer shell.
(atoms have a) full outer shell / stable arrangement of electrons
(c)Answer: 2
2
(d)Answer: Ar
Question 2Medium3 marks
Hydrogen and helium are both less dense than air, so either gas could be used to fill an airship. Densities at room temperature: hydrogen 0.08 g/dm3, helium 0.17 g/dm3, air 1.2 g/dm3. Hydrogen burns explosively in air. Helium is a noble gas.
Evaluate the use of hydrogen and helium to fill passenger airships.[3]
Show the answer and mark scheme
Answer: Hydrogen is less dense so gives slightly more lift, but it can burn explosively; helium is unreactive because its atoms have a full outer shell, so it is much safer. Helium is the better choice because safety matters more than the small difference in lift.
hydrogen is less dense than helium, so it would give (slightly) more lift
hydrogen is flammable / burns explosively, so it is dangerous if there is a spark or flame
helium does not burn / is unreactive, so it is much safer
helium is unreactive because its atoms have a stable arrangement of electrons / a full outer shell
judgement: helium is the better choice for passenger airships, because safety matters more than the small difference in lift