AQA GCSE Chemistry Chemistry Paper 1 (Higher), June 2025: Question 1
9 marks · Low Demand difficulty · Short Answer
Answer questions about periodic table trends, electronic configurations, Mendeleev's table, noble gases, isotopes, and relative atomic mass.
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Question text
01 This question is about elements in the periodic table.
01.1 Describe where the non-metallic elements are found in the periodic table.
[1 mark]
01.2 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 3
01.3 A sodium atom can be represented as 23Na
Complete Figure 1 to show the electronic structure of a sodium atom.
[1 mark]
Figure 1
01.4 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]
01.5 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.
01.6 What is meant by ‘isotopes’?
*03Answer in terms of subatomic particles.*
[2 marks]
01.7 Table 1 shows the mass numbers and percentage abundances of the isotopes of X.
Table 1
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 1
AO /
Question Answers Extra information Mark
Spec. Ref.
01.1 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.
01.2 a melting point below 100 °C 1 AO3
4.1.2.3
4.2.2.7
4.2.2.8
AO /
Spec. Ref.
01.3 allow any combination of ×, , 1 AO1
o, e(–) for electrons 4.1.1.7
AO /
Spec. Ref.
01.4 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 element(s) for
Group 6 / 7 elements
• iodine has different properties
to Group 6 elements allow converse arguments in
terms of tellurium
AO /
Spec. Ref.
01.5 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.
01.6 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
8 neutrons
AO /
Spec. Ref.
01.7 ~115 1 AO2
4.1.1.6
Total Question 1 9
How to answer it
Periodic Table, Atomic Structure & Isotopes
What this question tests
- Recalling the distribution of metals and non-metals on the periodic table.
- Identifying typical vs atypical physical properties of metals.
- Deducing and drawing electronic configurations from atomic numbers.
- Understanding Mendeleev's historical arrangement based on chemical properties.
- Explaining noble gas unreactivity in terms of electronic stability.
- Defining isotopes accurately using the terms protons and neutrons.
- Estimating relative atomic mass (Aᵣ) from isotopic abundances.
Location of Non-Metals in the Periodic Table
AQA Specification Reference: 4.1.2.3
✅ Correct Answer
Towards the right and the top.
❌ Common Errors
- Writing only "on the right" (missing "top").
- Confusing non-metals with transition metals (central block).
Atypical Metallic Properties (Gallium)
AQA Specification Reference: 4.1.2.3 / 4.2.2.7
✅ Correct Answer
Tick: A melting point below 100 °C
💡 Key Knowledge
Most metals have giant metallic lattice structures with strong electrostatic attractions between positive ions and delocalised electrons, leading to high melting points. Gallium has an unusually low melting point (~30 °C) and will melt in your hand.
🧠 Exam Technique
Notice the negative in the question: "is not typical". Most metals conduct electricity, form positive ions, and have high boiling points. Eliminate typical properties to find the odd one out.
Drawing Sodium's Electronic Structure
AQA Specification Reference: 4.1.1.7
✅ Correct Answer
A completed diagram showing a total of 11 electrons arranged as 2, 8, 1:
- Innermost shell: 2 electrons
- Second shell: 8 electrons (best drawn as 4 pairs)
- Outermost shell: 1 single electron
🧠 Exam Technique
Sodium is given as ²³₁₁Na . Always use the bottom number (atomic number = 11) for the number of electrons in an atom, NOT the top mass number (23).
❌ Common Errors
- Using the mass number (23) and drawing 23 electrons.
- Overcrowding inner shells beyond their maximum capacity (2, 8, 8).
Mendeleev's Periodic Table: Tellurium & Iodine
AQA Specification Reference: 4.1.2.2
✅ Correct Answer
Any one from:
- So that elements (tellurium and iodine) were placed in groups with similar properties.
- Because iodine has similar properties to other Group 7 elements (halogens).
- Because iodine has different properties to Group 6 elements.
❌ Common Errors
Historical Anachronism: Students often state "because iodine has fewer protons" or "because of atomic number". Mendeleev had no knowledge of protons, neutrons, or electrons! Any mention of atomic structure gets zero credit here.
Unreactivity of Group 0 (Argon)
AQA Specification Reference: 4.1.2.4
✅ Correct Answer
- Argon has a full outer shell of electrons (or 8 electrons in its outer shell / energy level) [1 mark].
- Therefore, it has a stable arrangement of electrons (or does not need to lose, gain, or share electrons) [1 mark].
❌ Common Errors
- Writing "it has no outer electrons" instead of a full outer shell.
- Writing only "it is a noble gas" without referring to the electrons.
Definition of Isotopes
AQA Specification Reference: 4.1.1.5
✅ Correct Answer
- Atoms with the same number of protons (or atoms of the same element) [1 mark].
- (but with) different numbers of neutrons [1 mark].
🧠 Exam Technique
The question specifies: "Answer in terms of subatomic particles". Mentioning "same atomic number but different mass number" does not explicitly name the subatomic particles and risks losing marks.
❌ Common Errors
- Referring only to electrons. (Ignore "same electrons" unless protons are explicitly stated).
- Vaguely stating "different masses" rather than naming neutrons.
Estimating Relative Atomic Mass
AQA Specification Reference: 4.1.1.6
✅ Correct Answer
Tick: ~115
📐 Step-by-Step Calculation
- Identify abundance data:
• Mass 113: 4%
• Mass 115: 96% - Calculate weighted average:
Aᵣ = [(113 × 4) + (115 × 96)] ÷ 100
Aᵣ = [452 + 11040] ÷ 100 = 114.92 - Determine closest estimate:
114.92 is extremely close to ~115.
🧠 Quick Estimation Tip
Because 96% of element X is the 115 isotope, the average mass must be very close to 115. You don't even need a full calculation to spot that ~115 is the only sensible estimate!
Topics
Chemistry · C1: Atomic Structure and the Periodic Table
Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 1 (Higher), June 2025. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.