AQA GCSE Chemistry Chemistry Paper 1 (Foundation), June 2022: Question 1

9 marks · Low Demand difficulty · Short Answer

Identify subatomic particles in an atom diagram, determine proton and neutron numbers, calculate the relative atomic mass of an element from isotopic abundance, identify the element, and define isotopes.

Practise this question

Question

Question 1 includes five sub-questions: 01.1 shows Figure 1, a diagram of an atom with electrons on shells labelled A, an inner electron shell labelled C, a shaded particle in the nucleus labelled B, and an unshaded particle marked with a plus sign in the nucleus labelled D, asking students to match 'Neutron' and 'Proton' to letters A, B, C, or D. 01.2 gives an atom with atomic number 9 and mass number 19, asking to select the number of electrons and neutrons from a box containing numbers 1, 9, 10, 19, and 28. 01.3 presents Table 1 showing isotope A with mass number 39 and percentage abundance 93.3% and isotope B with mass number 41 and abundance 6.7%, and provides the formula for relative atomic mass, asking to calculate Ar to 3 significant figures. 01.4 asks to suggest the identity of element Z using the periodic table. 01.5 asks to complete a sentence about isotopes having different numbers of neutrons.
Question text

01 This question is about atoms.

01.1 Figure 1 represents an atom of an element.

Figure 1

Draw one line from each name to the correct label.

[2 marks]

Name Label

A

Neutron

B

Proton C

3 D

01.2 An atom of element Y has:

• an atomic number of 9

• a mass number of 19.

Give the number of electrons and the number of neutrons in this atom.

Choose answers from the box.

[2 marks]

19 10 19 28

Number of electrons

Number of neutrons

Table 1 shows information about two isotopes of element Z.

Table 1

Percentage

Mass number

abundance (%)

Isotope A 39 93.3

Isotope B 41 6.7

01.3 Calculate the relative atomic mass (Ar) of element Z.

Use Table 1 and the equation:

(mass number × percentage) of isotope A + (mass number × percentage) of isotope B

Ar =

Give your answer to 3 significant figures.

[3 marks]

Ar (3 significant figures) =

*0031.*4 Suggest the identity of element Z.

Use the periodic table.

[1 mark]

Element Z

01.5 Complete the sentence.

Choose the answer from the box.

[1 mark]

electrons neutrons protons

*04* Isotopes of the same element have different mass numbers because the isotopes

have different numbers of .

Mark scheme

Show the mark scheme Mark scheme for Question 1: 01.1 awards 1 mark for Neutron linked to B and 1 mark for Proton linked to D. 01.2 awards 1 mark for 9 electrons and 1 mark for 10 neutrons. 01.3 awards 1 mark for setting up the equation ((39 × 93.3) + (41 × 6.7)) / 100, 1 mark for calculating 39.134, and 1 mark for rounding to 39.1. 01.4 awards 1 mark for potassium / K (allows error carried forward from 01.3). 01.5 awards 1 mark for 'neutrons'. Total = 9 marks.

Question 1

AO /

Question Answers Extra information Mark

Spec. Ref.

01.1 AO1

4.1.1.4

do not accept more than one line from a box on the left

AO /

Spec. Ref.

01.2 (number of electrons) 9 1 AO2

4.1.1.5

(number of neutrons) 10 1

AO /

Spec. Ref.

(relative atomic mass =) allow (relative atomic mass =)

01.3 (39 × 93.3) + (41 × 6.7) (3638.7) + (274.7) 1 AO2

Mark with 100 100 4.1.1.6

question

01.4 allow (relative atomic mass =)

36.387 + 2.747

= 39.134 1

= 39.1 allow an answer correctly 1

rounded to 3 significant figures

from an incorrect calculation

which uses all the values in

Table 1

AO /

Spec. Ref.

01.4 potassium / K allow ecf from question 01.3 1 AO3

4.1.1.1

Mark with

question

01.3

AO /

Spec. Ref.

01.5 neutrons 1 AO1

4.1.1.5

Total Question 1 9

How to answer it

Atomic Structure, Isotopes and Relative Atomic Mass

📋 WHAT THIS QUESTION TESTS

This question assesses fundamental knowledge from GCSE Chemistry Specification Topic 1 (Atomic Structure and the Periodic Table):

  • Identifying subatomic particles (protons, neutrons, electrons) and their location in an atom.
  • Deducing the number of subatomic particles using atomic number and mass number.
  • Calculating relative atomic mass (Aᵣ) from isotopic abundance data to a specified number of significant figures.
  • Using calculated relative atomic mass to identify an element on the Periodic Table.
  • Recalling the scientific definition of isotopes.
QUESTION 01.1 • 2 MARKS

Identifying Subatomic Particles in an Atom

Matching labels A, B, C, D to Proton and Neutron

Diagram Layout: Figure 1 shows a central nucleus with outer electron shells containing crosses (× labelled A), an electron shell ring (labelled C), neutral shaded particles in the nucleus (labelled B), and particles marked with a “+” sign in the nucleus (labelled D).

✅ Correct Matches

  • Neutron → B [1 mark]
  • Proton → D [1 mark]
Mark allocation: 1 mark per correct line drawn. Note: If more than one line is drawn from a name box, no marks are awarded for that box.

💡 Key Knowledge

  • Protons: Located in the nucleus; have a positive charge ( + sign).
  • Neutrons: Located in the nucleus; neutral (no charge/plain circle).
  • Electrons: Located in shells orbiting the nucleus (represented by ×, label A).
  • C: Represents the electron shell/orbit, not a particle.

🧠 Exam Technique

Always use a ruler to draw neat, direct lines. Look carefully at particle markings: the plus sign ( + ) directly clues you in to the proton's positive charge.

❌ Common Errors

  • Confusing B and D by ignoring the plus sign inside particle D.
  • Selecting A (electron) or C (electron shell) instead of nuclear particles.
  • Drawing two lines from one box, instantly forfeiting that mark.
QUESTION 01.2 • 2 MARKS

Deducing Electrons and Neutrons from Nuclear Symbols

Element Y: Atomic Number = 9, Mass Number = 19

✅ Correct Answers

  • Number of electrons = 9 [1 mark]
  • Number of neutrons = 10 [1 mark]
Options available: 1, 9, 10, 19, 28. Answers must come directly from this list.

📐 Calculations

  1. Electrons: In any neutral atom, electrons = protons = atomic number . Therefore, electrons = 9.
  2. Neutrons: mass number − atomic number
    19 − 9 = 10.

🧠 Exam Technique

Commit the two core atomic equations to memory:

  • Atomic Number = Protons = Electrons
  • Mass Number = Protons + Neutrons

❌ Common Errors

  • Adding the two numbers together ( 19 + 9 = 28 ) instead of subtracting to find neutrons.
  • Choosing 19 for electrons (confusing mass number with atomic number).
QUESTION 01.3 • 3 MARKS

Calculating Relative Atomic Mass (Aᵣ)

Data: Isotope A (mass 39, 93.3%), Isotope B (mass 41, 6.7%)

📐 Step-by-Step Calculation

  1. Step 1: Substitute values into the given equation
    Aᵣ = [(39 × 93.3) + (41 × 6.7)] / 100
    Aᵣ = [3638.7 + 274.7] / 100 [1 mark]
  2. Step 2: Calculate full unrounded value
    3913.4 / 100 = 39.134 [1 mark]
  3. Step 3: Round to 3 significant figures
    39.134 → 3rd figure is 1, followed by 3 (< 5)
    Final Answer = 39.1 [1 mark]

✅ Mark Breakdown

  • Mark 1: Correct expression: (39 × 93.3) + (41 × 6.7) / 100 or (3638.7 + 274.7) / 100
  • Mark 2: Calculating 39.134
  • Mark 3: Final answer rounded to 3 sig figs: 39.1
Error Carried Forward (ECF): The 3rd mark can be awarded for correctly rounding an incorrect calculation to 3 significant figures, as long as all values from Table 1 were used.

🧠 Exam Technique: Sanity Check

Isotopes are 39 and 41. The average must lie between 39 and 41. Because 39 has an abundance of 93.3%, the answer must be very close to 39. An answer of 39.1 makes complete chemical sense.

❌ Common Errors

  • Ignoring Significant Figures: Leaving the answer as 39.134 loses the final mark.
  • Rounding incorrectly: Writing 39 (2 sig figs) instead of 39.1 (3 sig figs).
  • Order of operations error: Dividing only the second term by 100 instead of the entire numerator sum on a scientific calculator.
QUESTION 01.4 • 1 MARK

Identifying Element Z

Using the calculated Aᵣ and the Periodic Table

✅ Correct Answer

Potassium or symbol K [1 mark]

Note: Allow “ecf” (error carried forward) from your calculated Aᵣ value in question 01.3. For example, if a student wrongly calculated 40.1, “calcium” / “Ca” would be accepted.

💡 Key Knowledge

  • On the GCSE Periodic Table, look for the element with a relative atomic mass (top number) closest to 39.1 (or 39).
  • Potassium (atomic number 19) has a relative atomic mass of 39.
  • Do not confuse atomic number (protons) with relative atomic mass when scanning the Periodic Table!
QUESTION 01.5 • 1 MARK

Definition of Isotopes

Completing the definition sentence

✅ Correct Sentence

Isotopes of the same element have different mass numbers because the isotopes have different numbers of neutrons. [1 mark]

Word box choices: electrons • neutrons • protons

💡 Key Knowledge & Definition

  • Definition of Isotopes: Atoms of the same element that have the same number of protons but a different number of neutrons.
  • Because they have the same number of protons and electrons, isotopes have identical chemical properties.
  • Because they have different numbers of neutrons, they have different physical masses (mass numbers).

❌ Common Misconceptions

Choosing protons: If the number of protons changes, it becomes a completely different element altogether! Choosing electrons: Changing electron numbers creates an ion, not an isotope.

Topics

Chemistry · C1: Atomic Structure and the Periodic Table

Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 1 (Foundation), June 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.