AQA GCSE Chemistry Chemistry Paper 1 (Foundation), June 2025: Question 8
9 marks · Low Demand difficulty · Short Answer
Answer questions about the periodic table, electronic configurations, Mendeleev's table, isotopes, and estimating relative atomic mass.
Practise this questionQuestion
Question text
08 This question is about elements in the periodic table.
08.1 Describe where the non-metallic elements are found in the periodic table.
[1 mark]
08.2 Gallium (Ga) is a metallic element in Group 3.
Which of these properties of gallium is not typical of most metals?
[1 mark]
Tick ( ) one box.
A boiling point above 1000 °C
A melting point below 100 °C
Conducts electricity when solid
Forms positive ions 31
08.3 A sodium atom can be represented as 23Na
Complete Figure 12 to show the electronic structure of a sodium atom.
[1 mark]
Figure 12
08.4 Mendeleev created an early periodic table.
Mendeleev placed most of the elements in order of atomic weight.
Tellurium and iodine were not placed in order of atomic weight.
Why did Mendeleev not place tellurium and iodine in order of atomic weight?
[1 mark]
08.5 Argon is an element in Group 0 of the periodic table.
Explain why argon is unreactive.
[2 marks]
An element X consists of two isotopes.
08.6 What is meant by ‘isotopes’?
*31Answer in terms of subatomic particles.*
[2 marks]
08.7 Table 5 shows the mass numbers and percentage abundances of the isotopes of X.
Table 5
Mass number Percentage abundance (%)
113 4
115 96
Which is the closest estimate to the relative atomic mass of X?
[1 mark]
Tick ( ) one box.
∼113 ∼114 ∼115
Mark scheme
Show the mark scheme
Question 8
AO /
Question Answers Extra information Mark
Spec. Ref.
08.1 towards the right and the top allow a description of the 1 AO1
position in the periodic table 4.1.2.3
allow in Groups (3) 4 to 0
AO /
Spec. Ref.
08.2 a melting point below 100 °C 1 AO3
4.1.2.3
4.2.2.7
4.2.2.8
AO /
Spec. Ref.
08.3 allow any combination of ×, , 1 AO1
o, e(–) for electrons 4.1.1.7
AO /
Spec. Ref.
08.4 ignore reference to atomic
structure
any one from: 1 AO1
4.1.2.2
• so elements / tellurium /
iodine were in groups with
similar properties
• iodine has similar properties
to Group 7 elements allow named elements for
Group 6 / 7 elements
• iodine has different properties
to Group 6 elements allow converse arguments in
terms of tellurium
AO /
Spec. Ref.
08.5 allow energy level for shell AO1
4.1.2.4
argon has a full outer shell (of allow argon has eight outer shell 1
electrons) electrons
ignore argon has no outer shell
electrons
(so argon) has a stable allow (so argon) does not gain / 1
arrangement of electrons lose / share electrons
or
(so argon) has a stable
electronic structure
AO /
Spec. Ref.
08.6 atoms with the same number of allow atoms of the same 1 AO1
protons element 4.1.1.5
allow atoms with the same
atomic number
ignore atoms with the same
number of electrons
(but with) different numbers of 1
neutrons 23
AO /
Spec. Ref.
08.7 ~115 1 AO2
4.1.1.6
Total Question 8 9
How to answer it
Periodic Table, Electronic Structure & Isotopes
Core chemistry foundations from AQA Topic 1 (Atomic Structure and the Periodic Table):
- Periodic Table geography: Locating metals vs non-metals.
- Physical properties: Distinguishing typical metallic properties from anomalies.
- Electronic configuration: Deducing and drawing electron shell arrangements (2,8,1 for sodium).
- History of the Periodic Table: Understanding why Mendeleev swapped element orders based on chemical properties.
- Group 0 stability: Explaining the unreactivity of noble gases via full outer electron shells.
- Isotopes & Relative Atomic Mass: Defining isotopes using subatomic particles and estimating relative atomic mass (Aᵣ) from percentage abundance.
Location of Non-Metals
1 Mark • AO1 (Spec Ref: 4.1.2.3)
✅ Correct Answer
Towards the right and the top of the periodic table.
❌ Common Errors
- Stating only "on the right" without mentioning "top" (misses the stepped dividing line).
- Confusing left and right on the periodic table.
Atypical Metallic Property of Gallium
1 Mark • AO3 (Spec Ref: 4.1.2.3, 4.2.2.7)
✅ Correct Answer
A melting point below 100 °C (gallium famously melts in your hand at ~30 °C).
💡 Key Knowledge
Typical properties of metals include:
- High melting and boiling points (strong metallic bonding).
- Good electrical conductivity when solid (delocalised electrons).
- Forming positive ions (cations) by losing electrons.
🧠 Exam Technique
Read the question carefully: it asks which property is NOT typical of most metals. The other three options describe classic metallic characteristics.
Electronic Structure of Sodium (²³₁₁Na)
1 Mark • AO1 (Spec Ref: 4.1.1.7)
✅ Correct Diagram Description
A diagram showing shells filled as 2, 8, 1 :
- Innermost shell: 2 electrons (dots or crosses)
- Second shell: 8 electrons (paired up)
- Outer shell: 1 electron
❌ Common Errors
- Using the mass number (23) instead of the atomic number (11) to determine electron count.
- Overfilling the innermost shell (putting more than 2 electrons).
Mendeleev's Ordering of Tellurium & Iodine
1 Mark • AO1 (Spec Ref: 4.1.2.2)
✅ Correct Answer (Any one)
- So that elements were placed in groups with similar chemical properties.
- Because iodine has properties similar to Group 7 elements (halogens).
- Because iodine has properties different from Group 6 elements.
❌ Common Misconception
Examiner Warning: Ignore references to atomic structure, protons, or atomic number. Mendeleev organized his table in 1869—protons and subatomic particles were not yet discovered!
🧠 Exam Technique
Always focus on chemical properties when explaining Mendeleev's decisions. He prioritized matching group properties over strictly following atomic weights.
Why Argon is Unreactive
2 Marks • AO1 (Spec Ref: 4.1.2.4)
✅ Marking Breakdown
Mark 1: Argon has a full outer shell of electrons (or eight outer shell electrons / full outer energy level).
Mark 2: Therefore, it has a stable arrangement of electrons (or does not need to gain, lose, or share electrons).
❌ Common Errors
- Writing "argon has no outer shell electrons" (incorrect, it has 8).
- Only writing "it is in Group 0" without referring to electron arrangements.
- Forgetting the second mark: you must link the full shell to stability or lack of electron transfer/sharing.
Definition of Isotopes
2 Marks • AO1 (Spec Ref: 4.1.1.5)
✅ Marking Breakdown
Mark 1: Atoms with the same number of protons (or atoms of the same element / same atomic number).
Mark 2: But with different numbers of neutrons.
🧠 Exam Technique
The prompt explicitly states: "Answer in terms of subatomic particles". Mentioning "protons" and "neutrons" is mandatory. Do not base your answer solely on "different mass numbers".
❌ Common Errors
- Stating "different numbers of electrons" (isotopes have the same number of electrons).
- Saying "elements with different neutrons" rather than atoms of the same element.
Estimating Relative Atomic Mass (Aᵣ)
1 Mark • AO2 (Spec Ref: 4.1.1.6)
✅ Correct Answer
Tick box: ~115
📐 Calculation & Reasoning
- Inspect abundances: Isotope 113 is only 4%, whereas Isotope 115 is 96%.
- Estimate: Because 96% is the vast majority, the weighted average must be very close to 115.
- Check by formula:
Aᵣ = [(113 × 4) + (115 × 96)] ÷ 100
Aᵣ = (452 + 11040) ÷ 100 = 114.92 ≈ 115
❌ Calculation Trap
Do not calculate a simple arithmetic average: (113 + 115) ÷ 2 = 114. Relative atomic mass is a weighted average that accounts for abundance!
Topics
Chemistry · C1: Atomic Structure and the Periodic Table
Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 1 (Foundation), June 2025. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.