Atomic structure and mass spectrometry: Edexcel International A Level Chemistry questions

Every Edexcel International A Level Chemistry exam question on Atomic structure and mass spectrometry (specification points 2.1–2.7), 2019–2025, with its mark scheme and examiner’s report.

All 69 questions on Atomic structure and mass spectrometry, as a list

June 2025, AS Unit 1, Q1 (1 mark): Which row shows the numbers of neutrons and electrons in a bromide ion 79Br– ? Number of Number of neutrons electrons A 44 35 B 44 36 C 46 35 D 46 36
June 2025, AS Unit 1, Q6 (1 mark): Which is the correct order for the processes in a mass spectrometer? A deflection detection ionisation vaporisation B vaporisation ionisation deflection detecti
June 2025, AS Unit 1, Q22(d) (2 marks): Chlorine can be analysed in a mass spectrometer. On the grid shown, draw the spectrum you would expect to see for the molecular ion peaks for a chlorine molecul
January 2025, AS Unit 1, Q23(a)(i) (3 marks): Calculate the mass number of the fifth isotope of germanium. The relative atomic mass of germanium is 72.6. You must show your working. (3)
January 2025, AS Unit 1, Q23(a)(ii) (1 mark): Give the main reason why the answer in (a)(i) should not be quoted to more than 2 significant figures. (1)
January 2025, AS Unit 1, Q23(b) (4 marks): The radioactive decay of germanium‑76 forms stable atoms of selenium‑76. Compare and contrast the atomic structure of an atom of germanium‑76 with an atom of se
October 2024, AS Unit 1, Q9(a) (1 mark): An atom of hydrogen can be represented as 1H. What is the mass, in grams, of this hydrogen atom? (1) A 1.6725 × 10–24 B 1.6734 × 10–24 C 3.3473 × 10–24 D 3.3482
October 2024, AS Unit 1, Q9(b) (1 mark): Which of the particles would be deflected by an electric field? (1) A electrons only B electrons and protons only C neutrons and protons only D electrons, neutr
June 2024, AS Unit 1, Q16(a)(ii) (2 marks): Calculate the relative atomic mass of a sample of silicon, using the isotopic abundance data provided. Give your answer to 3 significant figures. Isotope Abunda
June 2024, AS Unit 1, Q16(a)(iii) (1 mark): In the mass spectrum of silicon, there is also a small peak at m / z = 14. Deduce the formula of this particle. (1)
June 2024, AS Unit 2, Q13 (1 mark): Bromine and chlorine each have two stable isotopes, 79Br, 81Br, 35Cl and 37Cl. Which statement is true? A the atomic radius of 81Br is greater than that of 79Br
January 2024, AS Unit 1, Q3 (1 mark): Which species does not contain a total of 16 neutrons? A a molecule of ethene, 12C2 1H4 B a molecule of oxygen, 16O2 C an atom of silicon, 30Si D an ion of sulf
January 2024, AS Unit 1, Q19(a) (2 marks): 2‑Chloropropane has a relative molecular mass of 78.5 g mol–1. Chlorine has two common isotopes, 35Cl and 37Cl. There are three times more 35Cl atoms than 37Cl
January 2024, AS Unit 1, Q20(a)(i) (4 marks): Calculate the relative abundance and hence the mass number of the third isotope. Give your answer to the appropriate number of significant figures. You must sho
January 2024, AS Unit 1, Q20(a)(ii) (1 mark): State one similarity and one difference between these isotopes. (1)
January 2024, AS Unit 1, Q20(a)(iii) (1 mark): State which of these isotopes would be deflected most in a mass spectrometer. Justify your answer. (1)
October 2023, AS Unit 1, Q1 (1 mark): An atom of 27 13Al forms the ion, Al3+. What are the numbers of protons, electrons and neutrons in this ion? protons electrons neutrons A 13 13 14 B 10 13 14 C
October 2023, AS Unit 1, Q8 (1 mark): In which region of a mass spectrometer are particles ionised? P Q + R recorder amplifier S A region P B region Q C region R D region S
October 2023, AS Unit 1, Q9 (1 mark): A sample of the element chlorine, Cl2, was analysed in a mass spectrometer. Chlorine has two isotopes. What is the total number of peaks, due to ions with a sin
January 2023, AS Unit 1, Q6 (1 mark): How many neutrons and electrons are there in 190 79Au2+? Neutrons Electrons A 111 77 B 111 81 C 190 79 D 190 77
January 2023, AS Unit 1, Q7 (1 mark): The mass spectrum of an element is shown. 70 60 50 40 Percentage abundance 30 20 10 0 89 90 91 92 93 94 95 96 97 m / z What is the relative atomic mass of this
October 2022, AS Unit 1, Q3 (1 mark): An atom of 15 7N forms a nitride ion, N3–. What are the numbers of protons, neutrons and electrons in this ion? Protons Neutrons Electrons A 7 8 7 B 7 8 4 C 7 8
October 2022, AS Unit 1, Q10(a) (1 mark): In which region of this mass spectrometer are the ions accelerated? (1) P Q electromagnet vaporised to vacuum sample pump R S amplifier chart recorder A region
October 2022, AS Unit 1, Q10(b) (1 mark): Four iron ions are present in a stream of ions in a mass spectrometer. The paths of these ions are shown. path 4 stream of ions path 3 path 1 path 2 Which of th
October 2022, AS Unit 1, Q10(c) (1 mark): Naturally‑occurring chlorine has two isotopes, 35Cl and 37Cl. How many peaks due to the singly-charged molecular ions are seen in the mass spectrum of chlorine,
October 2022, AS Unit 1, Q16(a) (2 marks): Naturally‑occurring germanium consists of five stable isotopes. Explain what is meant by the term isotopes. (2)
October 2022, AS Unit 1, Q16(b) (2 marks): The mass spectrum of a sample of germanium is shown. 40 36.7 30 27.4 Percentage 20.6 20 abundance 10 7.7 7.6 0 70 71 72 73 74 75 76 77 m / z Calculate the relat
June 2022, AS Unit 1, Q6(a) (1 mark): What is the number of electrons in a scandium ion, Sc+ ? (1) A 20 B 21 C 22 D 23
June 2022, AS Unit 1, Q6(b) (1 mark): In a mass spectrometer, scandium forms Sc+ and Sc2+ ions. What is the m / z value for the mass spectrum peak due to the Sc2+ ions? (1) A 22.5 B 33.0 C 45.0 D 90
June 2022, AS Unit 1, Q20(a) (1 mark): State what is meant by the term isotopes. (1)
June 2022, AS Unit 1, Q20(b) (2 marks): Complete the table to show the numbers of subatomic particles in the two isotopes of bromine. (2) Isotope Protons Neutrons Electrons bromine‑79 bromine‑81
June 2022, AS Unit 1, Q20(c)(ii) (2 marks): Describe the formation of the molecular ion of bromine in the mass spectrometer. Include an equation. State symbols are not required. (2)
June 2022, AS Unit 1, Q20(c)(iii) (2 marks): On the mass spectrum grid, draw the peaks for the bromine molecular ions, showing the relative peak heights. The bromine isotopes in this sample have the same r
June 2022, AS Unit 1, Q20(d) (3 marks): The percentage abundances of the isotopes in a different sample of bromine are shown. Isotope Percentage abundance bromine‑79 56.38 % bromine‑81 43.62 % Calcula
January 2022, AS Unit 1, Q20(b)(i) (2 marks): Complete the table to show the numbers of subatomic particles in the atoms of these two isotopes of copper. (2) Isotope Protons Neutrons Electrons 63Cu 65Cu
January 2022, AS Unit 1, Q20(b)(ii) (2 marks): Explain the term isotopes, using the information in the table. (2)
January 2022, AS Unit 1, Q20(b)(iii) (1 mark): State why the two isotopes of copper have the same chemical reactions. (1)
January 2022, AS Unit 1, Q20(b)(iv) (2 marks): The relative atomic mass of copper in this sample is 63.4. Calculate the percentage abundances of the isotopes 63Cu and 65Cu in this sample. You must show your
October 2021, AS Unit 1, Q3(a) (1 mark): Which process occurs in region R? (1) A the sample is vaporised using a heater B electrons are removed from molecules or atoms and positive ions are formed C el
October 2021, AS Unit 1, Q3(b) (1 mark): Which statement is correct for region T? (1) A ions with a greater mass have a smaller deflection B ions with a greater mass have a greater deflection C ions wi
October 2021, AS Unit 1, Q13(a)(i) (2 marks): Data obtained using the mass spectrum of silicon are shown. Isotope mass number Relative abundance 28 92.17 29 4.71 30 3.12 Calculate the relative atomic mass o
October 2021, AS Unit 1, Q13(a)(ii) (1 mark): Suggest a reason why there is a small peak in the mass spectrum of silicon at m / z = 14 (1)
October 2021, AS Unit 1, Q13(a)(iii) (1 mark): Complete the table to show the number of protons and neutrons in each isotope of silicon. Number of Number of Isotope protons neutrons 28Si 29Si 30Si (1)
June 2021, AS Unit 1, Q1 (1 mark): The numbers of subatomic particles present in four species W, X, Y and Z are given in the table. Number of Number of Species Number of protons neutrons electron
June 2021, AS Unit 1, Q2 (1 mark): Iodine exists as one isotope with mass number 127. Chlorine exists as two isotopes with mass numbers 35 and 37. How many molecular ion (ICl3 +) peaks are there
June 2021, AS Unit 1, Q3 (1 mark): The mass spectrum of a sample of an element has only two peaks. 80 70 60 50 Relative 40 abundance 30 20 10 0 190 191 192 193 194 m / z What is the approximate r
June 2021, AS Unit 1, Q24(a) (1 mark): Complete the table to show the numbers of subatomic particles in 56Fe2+. (1) Number of protons Number of neutrons Number of electrons
June 2021, AS Unit 1, Q24(b) (2 marks): A sample of iron contains the following isotopes. Isotope Percentage abundance 54Fe 5.84 56Fe 91.68 57Fe 2.17 58Fe 0.31 Calculate the relative atomic mass of th
June 2021, AS Unit 2, Q22(c)(i) (2 marks): Give the reason for the ratio of peak heights at m / z values of 102, 100 and 98. (2)
June 2021, AS Unit 2, Q22(c)(ii) (1 mark): Suggest an identity for the peak at m / z = 63. (1)
June 2021, AS Unit 2, Q22(c)(iii) (1 mark): The peak at m / z = 65 has been omitted. Draw on the mass spectrum the peak at m / z = 65, showing its relative intensity. (1)
January 2021, AS Unit 1, Q5 (1 mark): Which of these atoms has the most neutrons? 49In A 115 B 124 50Sn C 123 51Sb D 124 52Te
January 2021, AS Unit 1, Q18(d)(i) (2 marks): State what is meant by the term isotopes, in terms of subatomic particles. (2)
January 2021, AS Unit 1, Q18(d)(ii) (2 marks): Calculate the relative atomic mass of sulfur in this sample. Give your answer to two decimal places. (2)
January 2021, AS Unit 1, Q18(e)(i) (1 mark): Calculate the number of sulfur atoms in the molecular ion. You must show your working. (1)
January 2021, AS Unit 1, Q18(e)(ii) (2 marks): Suggest the formula of the most stable ion shown by this spectrum. (2)
October 2020, AS Unit 1, Q6(a) (1 mark): What is the Ar of the element? (1) A 42.0 B 48.0 C 63.6 D 64.0
October 2020, AS Unit 1, Q6(b) (1 mark): Which species could be responsible for the peak at m / z = 32.5? (1) A 32S+ B 63Cu2+ C 65Cu2+ D 98Tc3+
January 2020, AS Unit 1, Q1 (1 mark): How many protons, neutrons and electrons are in a 37Cl– ion? Protons Neutrons Electrons A 17 20 16 B 17 20 17 C 17 20 18 D 20 17 21
January 2020, AS Unit 1, Q2 (1 mark): A sample of an element X contains only the isotopes shown. Isotope Percentage abundance 58X 68.077 60X 26.223 61X 1.140 62X 3.634 64X 0.926 What is the relative
January 2020, AS Unit 1, Q18(f)(i) (2 marks): Complete the mass spectrum for a sample of chlorine gas to show the expected molecular ion peaks due to Cl2 + . (2) 100 90 80 70 60 Relative 50 abundance 40 30
January 2020, AS Unit 1, Q18(f)(ii) (2 marks): Suggest why there could be a small peak at m / z = 36 in the mass spectrum of chlorine gas. (2)
June 2019, AS Unit 1, Q8 (1 mark): Which statement about subatomic particles is correct? A neutral atoms always contain the same number of protons and electrons B neutral atoms always contain the
June 2019, AS Unit 1, Q10 (1 mark): Isotopes are atoms of an element that have different A electronic structures B numbers of electrons C numbers of protons D numbers of neutrons
June 2019, AS Unit 1, Q11 (1 mark): The two stable isotopes of bromine have relative masses of 79 and 81. Which is the correct pattern of peaks in the mass spectrum of molecular bromine? Relative
June 2019, AS Unit 1, Q12 (1 mark): The mass spectrum of a sample of silicon is shown. Relative abundance 28 29 30 m / z What is the best estimate for the relative atomic mass of silicon in this s
January 2019, AS Unit 1, Q1 (1 mark): The hydroxide ion, OH−, has a total of 9 protons. How many neutrons and electrons are there in this ion? Number of neutrons Number of electrons A 8 8 B 8 10 9 8
January 2019, AS Unit 1, Q2 (1 mark): A sample of silicon contains the following isotopes. Isotope Percentage abundance 28Si 81.21 29Si 14.10 30Si 4.69 What is the relative atomic mass of silicon, t
January 2019, AS Unit 1, Q24(c)(i) (2 marks): A sample of nitrogen trichloride contained only nitrogen atoms with mass number 14, and chlorine atoms with mass numbers 35 and 37. Give the formula and mass/ch

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