AQA GCSE Chemistry Chemistry Paper 1 (Higher), 2024: Question 2
11 marks · Standard Demand difficulty · Short Answer
This multi-part question tests knowledge of Group 1, Group 0, and Group 7 elements, including electronic structures, reactions with water, properties of noble gases, and halogen displacement reactions.
Practise this questionQuestion
Question text
02 This question is about the periodic table.
Sodium and potassium are in Group 1 of the periodic table.
02.1 Give one similarity and one difference between the electronic structures of
sodium and potassium.
[2 marks]
Similarity
Difference
Group 1 elements react with water.
02.2 Give two observations made when potassium reacts with water.
[2 marks]
02.3 Potassium hydroxide solution is produced when potassium reacts with water.
What is the colour of universal indicator when added to potassium hydroxide solution?
Give one reason for your answer.
[2 marks]
Colour of universal indicator
Reason
Table 1 shows the densities of some of the elements in Group 0 of the periodic table.
Table 1
*05* Element Atomic number Density in mg/cm3
Helium 2 0.2
Neon 10 0.8
Argon 18 1.6
Krypton 36 X
Xenon 54 5.4
Radon 86 9.1
02.4 Plot the data from Table 1 on Figure 1.
[2 marks]
Figure 1
02.5 Estimate the density (X) of krypton.
Use Figure 1 and Table 1.
*06* [1 mark]
Density = mg/cm3
02.6 The elements in Group 7 are called the halogens.
A more reactive halogen can displace a less reactive halogen from a solution of its
salt.
Which combination of solutions will produce a reaction when mixed?
[1 mark]
Tick ( ) one box.
Chlorine and potassium fluoride
Chlorine and potassium bromide
Bromine and potassium fluoride
Bromine and potassium chloride
02.7 Which of the following describes the trends going down Group 7?
[1 mark]
Tick ( ) one box.
Relative molecular mass decreases and boiling point decreases.
Relative molecular mass decreases and boiling point increases.
Relative molecular mass increases and boiling point decreases.
Relative molecular mass increases and boiling point increases.
Mark scheme
Show the mark scheme
Question 2
AO /
Question Answers Extra information Mark
Spec. Ref.
02.1 allow energy level for shell AO1
4.1.2.1
(similarity)
both have one outer (shell) allow same number of outer 1
electron (shell) electrons
(difference)
sodium has 3 shells but allow potassium has more shells 1
potassium has 4 shells allow (different) number of shells
AO /
Spec. Ref.
02.2 any two from: 2 AO1
• effervescence / bubbles / ignore gas produced 4.1.2.5
fizzing 4.4.1.2
• (potassium) floats
• (potassium) moves around
• (potassium) becomes smaller
• (potassium) melts allow (potassium) forms a ball
• flame ignore colour of flame
• explosion
AO /
Spec. Ref.
02.3 blue / violet / purple 1 AO2
(the solution is) alkaline allow (the solution) contains 1 AO1
OH− (ions)
allow (the solution) contains 4.1.2.5
hydroxide ions– – – 4.4.2.4
allow the solution is basic
AO /
Spec. Ref.
02.4 all five points correctly plotted allow a tolerance of ± ½ a small 2 AO2
square 4.1.2.4
allow 1 mark for three or four
points correctly plotted
AO /
Spec. Ref.
02.5 3.4 (mg/cm3) allow a value in the range 3.0 to 1 AO3
3.8 (mg/cm3) 4.1.2.4
AO /
Spec. Ref.
02.6 chlorine and potassium bromide 1 AO2
4.1.2.6
AO /
Spec. Ref.
02.7 relative molecular mass 1 AO1
increases and boiling point 4.1.2.6
increases
Total Question 2 11
How to answer it
Periodic Table: Groups 1, 7, and 0
What this question tests
This question assesses your understanding of the Periodic Table, specifically:
- Electronic structures of Group 1 elements.
- Observations and products of the reaction between Alkali Metals and water.
- Data handling: plotting graphs and estimating values from trends.
- Reactivity and physical property trends in Group 7 (Halogens).
Electronic Structure of Sodium and Potassium
💡 Key Knowledge
- Group Number: Tells you how many electrons are in the outer shell.
- Period Number: Tells you how many electron shells an atom has.
- Sodium (Na) is in Period 3; Potassium (K) is in Period 4.
✅ Correct Answers
Similarity: Both have 1 electron in their outer shell.
Difference: Sodium has 3 shells, but Potassium has 4 shells.
[2 marks]Reactions of Group 1 with Water
🧠 Exam Technique
An observation is something you see, hear, or feel. Don't just say "Hydrogen is made"—that's a fact, not an observation. Instead, say "fizzing" or "bubbles".
✅ Correct Answers
02.2 Observations (Any two):
- Effervescence / bubbles / fizzing
- Potassium floats or moves around
- Potassium melts into a ball
- Lilac flame (Potassium is unique for this!)
02.3 Indicator:
- Colour: Purple / Blue / Violet
- Reason: The solution is alkaline (contains OH⁻ ions).
❌ Common Errors
Students often forget that Group 1 metals float. They are less dense than water! Also, ensure you specify the flame colour for Potassium is lilac; simply saying "it catches fire" may not get the mark if a specific observation is required.
Graphing and Estimating (Group 0)
🧠 Plotting the Graph
To get full marks on Figure 1:
- Use a sharp pencil and mark points with a small 'x'.
- Check the scale: On the y-axis, 1 big square = 2 units, so 1 small square = 0.2 units.
- Draw a line of best fit. For this data, it should be a smooth curve or a very straight line through the points.
📐 Step-by-Step: Estimating Krypton (X)
- Find the Atomic Number for Krypton in Table 1 (it is 36).
- Go to 36 on the x-axis of your graph.
- Move vertically up until you hit your line of best fit.
- Move horizontally to the left to read the Density on the y-axis.
- Expected Value: Approximately 3.4 mg/cm³ (Acceptable range: 3.0 to 3.8).
Group 7: Halogen Trends
💡 Displacement Rules
A more reactive halogen will displace a less reactive halogen from its salt.
Reactivity decreases as you go down Group 7:
Fluorine > Chlorine > Bromine > Iodine
✅ Correct Selections
02.6 Displacement: Chlorine and potassium bromide.
(Chlorine is above Bromine, so it is more reactive and can displace it).
02.7 Trends down Group 7: Relative molecular mass increases and boiling point increases.
❌ Common Errors
In 02.6, students often pick "Chlorine and potassium fluoride". This is wrong because Fluorine is more reactive than Chlorine, so Chlorine cannot displace it. The "lonely" halogen must be higher in the group than the one in the salt.
Topics
Chemistry
Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 1 (Higher), 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.