AQA GCSE Chemistry Chemistry Paper 1 (Higher), 2022: Question 5
11 marks · Standard Demand difficulty · Short Answer
Answer questions about Group 1 and Group 0 elements, including explaining reactivity trends, balancing a reaction with water, and calculating the relative atomic mass of neon from isotopic abundances.
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Question text
05 This question is about groups in the periodic table.
The elements in Group 1 become more reactive going down the group.
Rubidium is below potassium in Group 1.
05.1 Rubidium and potassium are added to water.
Predict one observation you would see that shows that rubidium is more reactive
than potassium.
[1 mark]
05.2 Explain why rubidium is more reactive than potassium.
[3 marks]
05.3 Complete the equation for the reaction of rubidium with water.
You should balance the equation.
[3 marks]
Rb + H2O → +
The noble gases are in Group 0.
05.4 Which is a correct statement about the noble gases?
[1 mark]
Tick ( ) one box.
*16* The noble gases all have atoms with eight electrons in the outer shell.
The noble gases have boiling points that increase going down the group.
The noble gases have molecules with two atoms.
The noble gases react with metals to form ionic compounds.
05.5 Table 1 shows information about the three isotopes of neon.
Table 1
Mass number Percentage abundance (%)
20 90.48
21 0.27
22 9.25
Calculate the relative atomic mass (Ar) of neon.
Give your answer to 3 significant figures.
[3 marks]
Relative atomic mass (3 significant figures) =
Mark scheme
Show the mark scheme
Question 5
AO /
Question Answers Extra information Mark
Spec. Ref.
05.1 allow converse statements for AO3
potassium 4.1.2.5
any one from: 1
• more vigorous bubbling (for
rubidium)
• bigger / brighter flame (for allow (rubidium) catches fire
rubidium) more quickly
allow (rubidium) moves around
more quickly
allow (rubidium) explodes
allow (rubidium) disappears
more quickly
allow (rubidium) melts more
quickly
AO /
Spec. Ref.
05.2 allow energy level for shell AO1
throughout 4.1.2.5
4.4.1.2
allow converse argument in
terms of potassium
(rubidium’s) outer shell / allow the (rubidium) atom is 1
electron is further from the larger
nucleus allow (rubidium) has more shells
(so) there is less (electrostatic) allow (so) there is more 1
attraction between the nucleus shielding between the outer
and the outer electron (in electron and the nucleus (in
rubidium) rubidium)
(so) the (outer) electron (in allow (so) less energy is needed 1
rubidium) is more easily lost to remove the (outer) electron
(in rubidium)
18 AO /
Spec. Ref.
ignore state symbols
05.3 AO2
2 Rb + 2 H2O → 2 RbOH + H2 allow multiples 3 4.1.1.1
4.1.2.5
allow 1 mark for H2 4.3.1.1
allow 1 mark for RbOH
AO /
Spec. Ref.
05.4 the noble gases have boiling 1 AO1
points that increase going down 4.1.2.4
the group
AO /
Spec. Ref.
05.5 (relative atomic mass =) allow (relative atomic mass =) AO2
1 4.1.1.6
(90.48 ×20)+(0.27 ×21)+(9.25 ×22) 1809.6 + 5.67 + 203.5
100 100
allow (relative atomic mass =)
18.096 + 0.0567 + 2.035
= 20.1877 1
= 20.2 allow an answer correctly 1
rounded to 3 significant figures
from an incorrect calculation
which uses all of the values in
Table 1
ignore units
Total Question 5 11
How to answer it
Group Trends & Isotopes Study Guide
AQA GCSE Chemistry Exam Prep
This question assesses your understanding of periodic table trends, specifically Group 1 (alkali metals) reactivity, Group 0 (noble gases) physical properties, writing and balancing chemical equations, and calculating the relative atomic mass (Aᵣ) of an element from isotopic abundance data.
Part (a) — Group 1 Observations
Question 05.1
Predict one observation you would see that shows that rubidium is more reactive than potassium when added to water.
✅ Correct Answers (Choose One)
- More vigorous bubbling / fizzing
- Bigger / brighter flame
- Catches fire more quickly
- Explodes
- Melts or disappears more quickly
💡 Exam Technique
Because the question asks you to show that rubidium is more reactive than potassium, your answer must use comparative language (e.g., "more vigorous", "faster", "brighter") or describe an extreme reaction like an "explosion".
Part (b) — Explaining Reactivity Trends
Question 05.2
Explain why rubidium is more reactive than potassium.
✅ Correct Answer Structure
- Rubidium's outer shell/electron is further from the nucleus (or rubidium has more shells/is a larger atom). [1 mark]
- Therefore, there is less electrostatic attraction between the positive nucleus and the outer electron. [1 mark]
- So, the outer electron is more easily lost. [1 mark]
🧠 Key Knowledge
Group 1 metals react by losing their single outer electron to form 1+ ions. As you go down the group:
- Atoms get larger (more shells).
- Outer electron is shielded by inner shells.
- Attraction to nucleus weakens, making it easier to lose the electron.
❌ Common Errors & Misconceptions
- Vague terms: Writing "it is further away" without specifying that it is the outer electron or outer shell that is further from the nucleus.
- Confusing groups: Do not confuse Group 1 with Group 7. In Group 7, reactivity decreases down the group because it is harder to gain an electron when there is more shielding.
Part (c) — Balancing Chemical Equations
Question 05.3
Complete and balance the equation for the reaction of rubidium with water:
Rb + H₂O → ? + ?
✅ Correct Balanced Equation
2Rb + 2H₂O → 2RbOH + H₂
• H₂ formula [1 mark]
• RbOH formula [1 mark]
• Correct balancing [1 mark]
📐 Step-by-Step Balancing
- Identify products: Alkali metal + water → metal hydroxide ( RbOH ) + hydrogen gas ( H₂ ).
- Unbalanced: Rb + H₂O → RbOH + H₂ (3 H on right, 2 H on left).
- Balance Hydrogens: Put a 2 in front of H₂O and RbOH to get 4 H on both sides: Rb + 2H₂O → 2RbOH + H₂ .
- Balance Rubidium: Put a 2 in front of Rb : 2Rb + 2H₂O → 2RbOH + H₂ .
❌ Common Equation Traps
Students often write hydrogen gas as H instead of the diatomic molecule H₂ . Another common mistake is writing the metal hydroxide formula incorrectly (e.g., RbO or RbO₂ ). Rubidium is in Group 1, so it forms Rb⁺ which pairs 1:1 with hydroxide OH⁻ .
Part (d) — Noble Gas Properties
Question 05.4
Which is a correct statement about the noble gases?
✅ Correct Statement
"The noble gases have boiling points that increase going down the group."
🧠 Why are the other options incorrect?
- "All have eight electrons in the outer shell" — False! Helium only has 2 outer electrons.
- "Have molecules with two atoms" — False! Noble gases are monatomic (exist as single atoms).
- "React with metals to form ionic compounds" — False! They are extremely unreactive (inert).
Part (e) — Relative Atomic Mass Calculation
Question 05.5
Calculate the relative atomic mass (Aᵣ) of neon using the isotope data below. Give your answer to 3 significant figures.
| Mass Number | Percentage Abundance (%) |
|---|---|
| 20 | 90.48 |
| 21 | 0.27 |
| 22 | 9.25 |
📐 Step-by-Step Calculation
Step 1: Multiply each mass number by its percentage abundance, then add them together:
(20 × 90.48) + (21 × 0.27) + (22 × 9.25)
= 1809.6 + 5.67 + 203.5 = 2018.77
Step 2: Divide the total by 100:
2018.77 / 100 = 20.1877
Step 3: Round to 3 significant figures:
20.2
• Correct expression/working [1 mark]
• Correct intermediate value (20.1877) [1 mark]
• Correct rounding to 3 sig figs (20.2) [1 mark]
❌ Calculation Traps
- Dividing by 3: Do not divide by the number of isotopes (3). You must divide by 100 because it is a weighted average based on percentages.
- Significant Figures: Leaving the answer as 20.1877 or rounding to 2 decimal places ( 20.19 ) will lose you the final mark. Always check the requested format!
Topics
Chemistry · C1: Atomic Structure and the Periodic Table
Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 1 (Higher), 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.