A-LevelChemistryAtomic structure9701/23 · May/June 2025 · Q110 Marks

The chemical properties of an element are related to the electronic configuration of its atoms.

(a)(i)Give the full electronic configuration of a fluorine atom.[1]
(a)(ii)Deduce the number of pairs of electrons in the second energy shell, n = 2, of an oxygen atom.[1]
(a)(iii)Draw the shape of the highest energy orbital that contains electrons in an atom of calcium.[1]
(b)(i)Write an equation to represent the first ionisation energy of sulfur.[1]
(b)(ii)Explain why the first ionisation energy of sulfur is less than the first ionisation energy of phosphorus.[2]
(b)(iii)Arrange the three species F¯, Ne and Na⁺ in order of increasing radius. Explain your answer. < smallest radius < largest radius[4]

Mark scheme

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

[1] 1s² 2s² 2p⁵
[1] 2 (pairs)
[1] [A drawn circle/sphere representing an s-orbital]
[1] S(g) → S⁺(g) + e⁻ OR S(g) – e⁻ → S⁺(g)
[2] M1 pair of electrons in a 3p orbital (in S) repel each other M2 outweighs the effect of increase in nuclear charge
[4] M1 Na⁺ < Ne < F⁻ M2 (all have) same number of electrons / isoelectronic M3 larger species has smaller nuclear charge / fewer protons M4 (so) smaller nuclear attraction (to outer electrons)

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