A-LevelChemistryChemical periodicity9701/22 · Oct/Nov 2021 · Q217 Marks

(a) Table 1 gives physical data for some of the Period 3 elements. [Figure 2.1]

(a)(i)Complete the row in the table labelled 'bonding present in element'. Use C = covalent, I = ionic, M = metallic, as appropriate.[1]
(a)(ii)Explain the difference between the first ionisation energies of the elements with atomic numbers 11 and 17.[2]
(a)(iii)Explain the difference between the first ionisation energies of the elements with atomic numbers 15 and 16.[2]
(a)(iv)Complete the row in the table labelled 'maximum oxidation number'.[1]
(a)(v)Explain the variation in anionic radius for the elements with atomic numbers 14 to 17.[2]
(b)Use the axes to sketch a graph that shows the trend in melting points of the elements with atomic numbers 11 to 17. [Figure 2.2][2]
(c)Dmitri Mendeleev published the first Periodic Table in 1869. Mendeleev used his knowledge of chemical periodicity to propose the properties of gallium, ³¹Ga, a Group 13 element. Table 2 gives some chemical and physical data of elements in Group 13. [Figure 2.3] Complete the table by predicting values for the missing data.[3]
(d)(i)Identify the formula of the salt formed when indium reacts with hydrochloric acid.[1]
(d)(ii)Construct an equation for the reaction of In₂O₃ with excess aqueous NaOH.[1]
(d)(iii)Draw a diagram that clearly shows the types of bond present in In₂Br₆(g).[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.

[1] M M M C C C C
[2] All 3 points correct scores two marks. Any 2 points scores one mark.
[2] • nuclear charge increases OR increasing proton number e.g. 17/Cl has a greater nuclear charge
[2] • describe the similarity in shielding between the two elements e.g. they have almost the same shielding
[2] • describe the overall effect in terms of greater nuclear attraction for (outer) electrons e.g. (outer) electrons are attracted more (strongly) to the nucleus
[2] M1 describes the difference between 1st IE of elements 15 and 16 (P and S) in terms of either: spin-pair repulsion (in element 16/S) OR electron pair repulsion (in element 16/S)
[2] M2 describes the location of the electron pair in the (3)p orbital which repel each other
[1] (+)1 (+)2 (+)3 (+)4 (+)5 (+)6
[2] M1 (anions have) same number of electrons (but increasing proton number)
[2] M2 increasing proton number / nuclear charge AND increasing attraction of nucleus for (outer) electrons OR (outer) electrons attracted more (strongly) to the nucleus AND because of increasing proton number/nuclear charge
[2] (Diagram showing sketch: Na, Mg, Al increasing, Si much higher peak, P, S decreasing, Cl very low)
[3] M1 density of 13Al: value within range 2.5–5.0 (g cm⁻³)
[3] M2 cationic radius of 31Ga: value within range 0.055–0.075 (nm)
[3] M3 boiling point of 49In: value within range 1500–2300 (K)
[1] InCl3
[1] In2O3 + 2NaOH + 3H2O → 2NaIn(OH)4
[2] M1 correct connectivity of In2Br6
[2] M2 showing the two correct dative covalent bonds