O-LevelChemistryMetals & Reactivity5070/22 · May/June 2021 · Q810 Marks

Lead is a metal with proton number 82.

(a)(i)Use the Periodic Table to state the number of occupied electron shells in an atom of lead.[1]
(a)(ii)Use the Periodic Table to state the number of electrons in the outer shell of an atom of lead.[1]
(b)Describe, with the aid of a labelled diagram, the metallic bonding in lead.[3]
(c)Give two physical properties of lead that are characteristic of all metals. 1. 2.[1]
(d)Lead(II) ethanoate is a white crystalline soluble salt. Name a suitable combination of an acid and an insoluble base which is used to prepare lead(II) ethanoate. acid base[1]
(e)Aqueous lead(II) ethanoate reacts with aqueous sodium iodide. A yellow precipitate of lead(II) iodide, PbI₂, is formed. Construct the ionic equation, with state symbols, for this reaction.[2]
(f)Explain why solid lead(II) iodide cannot be electrolysed.[1]

Mark scheme

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

[1] six
[1] four
[1] closely packed positive ions in regular arrangement (1)
[1] delocalised electrons / sea of electrons (1)
[1] strong attraction between the (positive) ions and the electrons (1)
[1] Any two for one mark: good electrical conductor good thermal conductor shiny / lustrous malleable ductile/can be made into wires
[1] ethanoic acid and lead(II) oxide or lead(II) hydroxide
[1] Pb²⁺(aq) + 2I⁻(aq) → PbI₂(s) (1)
[1] correct formulae for reactants and products and balanced (1)
[1] state symbols dependent on correct formulae (1)
[1] ions cannot move / no mobile ions

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