A-LevelChemistryAtomic structure9701/22 · Oct/Nov 2025 · Q110 Marks

Manganese, Mn, and its compounds are widely used in many chemical reactions.

(a)(i)Determine the number of protons, neutrons and electrons in an atom of manganese-55. number of protons ................................ neutrons ................................ electrons ................................[1]
(a)(ii)Define isotopes.[1]
(a)(iii)A sample of manganese from the Moon is found to contain manganese-53 in addition to manganese-55. State the two pieces of information needed to determine the relative atomic mass, Aᵣ, of manganese in this sample. 1 2[2]
(b)(i)The shorthand electronic configuration of manganese is [Ar] 3d⁵ 4s². Complete the full electronic configuration of manganese. 3d⁵ 4s²[1]
(b)(ii)Deduce the total number of unpaired electrons in an atom of manganese.[1]
(c)(i)Identify the species that is reduced in half-equation 2. Explain your answer.[2]
(c)(ii)The oxidation state of carbon in methanal is 0. Calculate the oxidation state of carbon in carbon dioxide.[1]
(c)(iii)Construct the ionic equation for the reaction of manganese(IV) oxide with methanal in acidic conditions.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2025). The mark or mark type is shown in brackets.

[1] 25 protons 30 neutrons 25 electrons
[1] (atoms of an element) with the same number of protons and different number of neutrons
[2] M1 (relative) isotopic mass. OR (relative isotopic) mass of Mn-55 and Mn-53 M2 (relative) abundance of each isotope
[1] 1s² 2s² 2p⁶ 3s² 3p⁶ (3d⁵ 4s²)
[1] 5
[1] Mn / MnO2 AND it gains electrons
[1] (+)4
[N/A] Due to an issue with question 1(c)(iii), the question has been removed from the question paper.

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