Topic 8 Practice Paper: The Periodic Table — mark scheme (print)

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QQ/IGCSE-CHEM/T8

IGCSE · Cambridge IGCSE Chemistry (Extended (Core + Supplement))

Mark scheme

The Periodic Table

Topic 8 Practice Paper · Maximum mark: 30

Notes for markers

Award one mark for each point marked [1], up to the marks shown for the part.
Accept answers worded differently that show the same understanding.
Units are required where the answer line shows one. ecf: allow an error carried forward.

Section A: Multiple-choice questions[10 marks]

Question	Answer
1	BPeriod 3 places the element in the third row, and Group VII in the halogen column: chlorine.	1
2	DSodium, magnesium and aluminium are metals while phosphorus, sulfur and argon are non-metals, so metallic character falls across the period.	1
3	AGroup III atoms lose their three outer electrons, giving Al³⁺.	1
4	CGroup I melting points decrease down the group: lithium melts at 180 °C, sodium at 98 °C and potassium at 63 °C.	1
5	ASodium is so reactive that it quickly tarnishes in air and reacts with moisture; oil keeps both air and water away.	1
6	CThe three halogens run gas (chlorine), liquid (bromine), solid (iodine) down the group, with chlorine pale yellow-green, bromine red-brown and iodine grey-black.	1
7	DBromine is less reactive than chlorine, so it cannot displace chloride ions; the bromine colour simply remains.	1
8	ATransition elements are dense, high-melting metals that form coloured compounds and often catalyse reactions.	1
9	CA catalyst provides a faster route for the reaction and is regenerated, so it is not consumed.	1
10	BThe last number in the configuration is the outer-shell count: eight, a complete shell, which explains argon’s unreactivity.	1

Section B: Structured questions[20 marks]

Question	Answer and marking points	Marks
11(a)	Lithium, then sodium, then potassium (least to most reactive). lithium < sodium < potassium [1]	1
11(b)	Potassium melts into a shining ball, fizzes rapidly and the hydrogen produced ignites with a lilac flame. melts / moves rapidly / fizzes strongly [1] hydrogen ignites with a lilac flame [1]	2
11(c)	For example, rubidium reacts even more violently with water than potassium; reactivity increases down the group. Also acceptable: lower melting point or higher density than potassium, extending those trends. a valid predicted property from the trends [1] correct justification quoting the trend [1]	2
	Total for Question 11	5
12(a)	The solution turns orange-brown as bromine is displaced. [1]	1
12(b)	No change — iodine is less reactive than bromine, so no displacement happens. no visible change / no reaction [1]	1
12(c)	Cl₂(aq) + 2Br⁻(aq) → 2Cl⁻(aq) + Br₂(aq) Cl₂(aq) + 2Br⁻(aq) → 2Cl⁻(aq) + Br₂(aq) with correct species [1] correctly balanced, with state symbols [1]	2
12(d)	Chlorine is the oxidising agent: it gains electrons, oxidising the bromide ions. chlorine, because it gains electrons / oxidises bromide [1]	1
	Total for Question 12	5
13(a)	Group I [1]	1
13(b)	period 4 [1]	1
13(c)	2,8,8 [1]	1
13(d)	argon [1]	1
	Total for Question 13	4
14(a)	Any two of: high density; high melting point; good electrical conductivity; hardness. any valid property such as high density [1] a second valid property such as high melting point [1]	2
14(b)	In FeO iron is +2 (iron(II) oxide); in Fe₂O₃ iron is +3 (iron(III) oxide). +2 in FeO / iron(II) oxide [1] +3 in Fe₂O₃ / iron(III) oxide [1]	2
14(c)	Vanadium, as vanadium(V) oxide, V₂O₅. vanadium(V) oxide / V₂O₅ [1]	1
14(d)	Its full outer shell makes it inert, so it will not react with the hot filament and the lamp lasts longer. inert / does not react with the hot filament [1]	1
	Total for Question 14	6

— End of mark scheme —