O-LevelChemistryBonding & Structure5070/22 · Oct/Nov 2021 · Q1010 Marks

This question is about elements in Group V of the Periodic Table. (a) The table shows some properties of the Group V elements. [Table 10.1] Use the information in the table to:

(a)(i)predict the density of antimony[1]
(a)(ii)suggest why it is difficult to predict the melting point of arsenic.[1]
(b)(i)The structure of two compounds of phosphorus, R and S, are shown. [Figure 10.2] Explain in terms of structure and bonding why compound R has a high melting point and compound S has a low melting point. compound R compound S[4]
(b)(ii)Explain why compound R conducts electricity when molten.[1]
(b)(iii)Draw a dot-and-cross diagram for a molecule of compound S. Show only the outer shell electrons.[1]
(c)An oxide of phosphorus has the formula P4O10- Calculate the percentage by mass of phosphorus in this compound.[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] values between 6.00 and 9.50 (inclusive of these values)
[1] there is no trend (down the group)
[4] R is an ionic structure / R has an ionic lattice / R is giant ionic (1)
R bonds (throughout lattice) are strong (1)
(dependent on the mention of ions / ionic for R)
S is a simple molecular structure / small molecule / simple molecule (1)
S weak forces between molecules (1)
[1] ions can move / has mobile ions
[1] 3 pairs of bonding electrons between each H and P AND 2 non-bonding electrons on P
[2] 43.7 (%) (2)
If 2 marks not scored 1 mark for molar mass of P4O10 = 284

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