Chemistry 5070 · O Level · Arrangement of elements

Arrangement of elements — practice question

The table summarises several properties of the elements in Group III of the Periodic Table. Element / proton (atomic) number / atomic radius (nm) / melting point (^{\circ}C) B: 5, 0.080, 2306 Al: 13, 0.125, 660 Ga: 31, 0.125, 30 In: 49, 0.150, 157 Tl: 81, 0.155, 304 Nh: 113, not given, not given
(a(i))[1]

Nihonium, Nh, has only just been discovered. Its atomic radius and melting point could not be measured because it is too radioactive. Estimate the atomic radius of Nh.

(a(ii))[1]

Explain, using data from the table, why estimating the melting point of nihonium is difficult.

(b)[1]

Boron has a giant covalent structure. Explain why boron has a high melting point.

(c(i))[1]

Aluminium is made by the electrolysis of molten aluminium oxide. Aluminium oxide contains Al$^{3+}$ and O$^{2-}$ ions. Describe the composition of the electrolyte used in this electrolysis.

(c(ii))[1]

Name the material used for the electrodes in this electrolysis.

(c(iii))[2]

Write equations for the reactions occurring at the: negative electrode positive electrode.

(d)[1]

Aluminium reacts with aqueous copper(II) chloride in a redox reaction. $\text{2Al(s)} + \text{3Cu}^{2+}(aq) \rightarrow \text{2Al}^{3+}(aq) + \text{3Cu(s)}$ Which particle is oxidised? Explain your answer.

(e)[2]

Explain why a piece of aluminium in water does not react.

(f)[4]

Aluminium chloride is a soluble salt. Describe how a pure sample of aluminium chloride crystals can be made from aluminium.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: 0.155-0.190 nm

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