Paper 4 Periodic Table Structured Practice
5 structured exam questions on the periodic table for IGCSE Chemistry Paper 4. Covers group trends, alkali metals, halogens, transition elements, and noble gases. Total: 25 marks.
Published by IGCSEChemistry.com.my
Chemistry teaching team: K. S. Tan (15+ years teaching IGCSE Chemistry) and Ms Yash (10+ years teaching IGCSE Chemistry) and Ms Kartini (15+ years teaching IGCSE Chemistry).
Mapped to Cambridge IGCSE Chemistry 0620 (2026–2028). Last updated 2026-08-19.
Five structured questions in the style of IGCSE Chemistry Paper 4, totalling 25 marks. Write your answers in full before checking the mark scheme.
Question 1 (5 marks)
The alkali metals (Group I) include lithium, sodium, and potassium.
(a) State two physical properties that are typical of Group I metals but unusual for metals. [2]
(b) Potassium reacts more vigorously with water than sodium. Explain this trend in terms of atomic structure. [3]
Mark scheme
(a) Any two from: low density / float on water [1]; soft / can be cut with a knife [1]; low melting point (compared with most metals) [1].
(b) Potassium has more electron shells / a larger atomic radius than sodium [1]. The outer electron is further from the nucleus and is more shielded by inner electrons [1]. Therefore the outer electron is lost more easily / less energy is needed to remove it, so potassium reacts more vigorously [1].
Total: 5 marks
Question 2 (6 marks)
The halogens (Group VII) include chlorine, bromine, and iodine.
(a) State the physical state and colour of each halogen at room temperature. [3]
(b) Explain the trend in reactivity of the halogens going down the group. [3]
Mark scheme
(a) Chlorine: green gas [1]. Bromine: red-brown / orange-brown liquid [1]. Iodine: grey/dark solid (gives purple vapour when heated) [1].
(b) Reactivity decreases down the group [1]. Going down the group, atoms get larger / have more electron shells [1]. It becomes harder for the nucleus to attract an extra electron into the outer shell because the outer shell is further from the nucleus and there is more shielding from inner electrons, so it is less easy to gain an electron and form a negative ion [1].
Total: 6 marks
Question 3 (5 marks)
Chlorine water is added to separate solutions of potassium bromide and potassium iodide.
(a) State the observation when chlorine water is added to potassium bromide solution. [1]
(b) Write the balanced equation for the reaction in part (a). [1]
(c) Explain why chlorine displaces bromine from potassium bromide. [1]
(d) Write the ionic equation for the reaction between chlorine and potassium iodide solution. [1]
(e) In this ionic equation, state which species is oxidised. Explain your answer. [1]
Mark scheme
(a) The solution turns orange / red-brown (due to bromine being produced) [1].
(b) Cl₂ + 2KBr → 2KCl + Br₂ [1]
(c) Chlorine is more reactive than bromine / chlorine is higher in Group VII, so it can displace bromine [1].
(d) Cl₂ + 2I⁻ → 2Cl⁻ + I₂ [1]
(e) Iodide ions (I⁻) are oxidised because they lose electrons (each I⁻ loses one electron to form I₂) [1].
Total: 5 marks
Question 4 (5 marks)
Compare transition elements with Group I metals.
(a) State three typical properties of transition elements. [3]
(b) Give one specific example of a transition element acting as a catalyst in an industrial process. Name the element and the process. [2]
Mark scheme
(a) Any three from: higher melting points / harder / denser than Group I metals [1]; form coloured compounds / ions (e.g. CuSO₄ is blue, FeCl₃ is yellow) [1]; can have variable oxidation states / form ions with different charges (e.g. Fe²⁺ and Fe³⁺) [1]; can act as catalysts [1].
(b) Iron is used as the catalyst in the Haber process (manufacture of ammonia) [1+1]. Or: Vanadium(V) oxide (V₂O₅) is used as the catalyst in the Contact process (manufacture of sulfuric acid) [1+1]. Or: Nickel is used as a catalyst in the hydrogenation of vegetable oils [1+1].
Total: 5 marks
Question 5 (4 marks)
The noble gases (Group 0/VIII) include helium, neon, and argon.
(a) Explain why the noble gases are unreactive in terms of their electron configuration. [2]
(b) State two uses of noble gases and explain why their unreactivity makes them suitable for each use. [2]
Mark scheme
(a) Noble gases have full/complete outer electron shells / stable electron configurations [1]. They have no tendency to gain, lose, or share electrons, so they do not form bonds with other atoms [1].
(b) Any two from: Argon is used in welding to provide an inert atmosphere / prevent the hot metal reacting with oxygen [1]. Helium is used in balloons/airships because it is less dense than air and non-flammable (safer than hydrogen) [1]. Neon is used in advertising signs / coloured lighting because it glows when electricity passes through it and does not react with the electrodes [1].
Total: 4 marks
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