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Marking Scheme
1.
2.
3.
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Examiner's Comments
This comment originally referred to question 8 on paper 4462/02 (12/06/2015)
1.
(a)
(b)
Only the more able candidates gained good marks here. Common incorrectanswers seen included BaOH2 and Fe2+.
We expected the explanation here of how a sodium atom becomes a sodiumion and likewise for bromine. Instead the majority of answers concentrated onthe attraction of the anion and the cation or some explanation of the formula.Hence answers such as 'same number of positive and negative ions', 'theircharge cancel each other out' and 'sodium becomes a positive ion and brominebecomes a negative ion which balance each other out' gained no credit.
Only weaker candidates struggled with this question. Part (a) was not answered as well as part (b).
not using two potassium atoms
showing the outer electron on the potassium atoms and the two transferred electrons on the sulfur in
the same diagram
either omitting the charge on the ions or getting the charges wrong.
This comment originally referred to question 5 on paper 4472/02 (13/01/2015)
2.
Common errors included:(a)
Generally well answered.(b)
This question was quite well answered. Generally, candidates concentrated on the bonding aspect and gave
diagrams showing electron transfer or, in a minority of cases, the crystal structure. The bonding diagrams
were well done though charges on the ions were sometimes omitted and electrons occasionally appeared in
two places simultaneously. Many went no further than this. The reason for the high melting point was generally
well described. However, when discussing electrical conductivity most referred to the ability of electrons to
move freely in the molten state and in solution.
This comment originally referred to question 9 on paper 4472/02 (14/05/2015)
3.
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(iii) Very well answered.
This comment originally referred to question 4 on paper 4472/01 (15/05/2014)
4. (i) A very well answered question.(a)
(ii) Poorly answered in general. 'Hydroxide', hydrogen oxide' and 'H2O' were common unacceptable
answers seen.
(i) A poorly answered question. The most common incorrect response was '14' - the total number of
bonding electrons.
(b)
(ii) Also poorly answered. A variety of incorrect numbers given here including '6' and '7'.
This comment originally referred to question 6 on paper 4472/02 (14/05/2015)
5. (a)
(b)
(c)
Poorly answered. Many candidates focused on diamond and ignored hydrogenaltogether. Vague statements that bonds in diamond are strong whilst those inhydrogen are weak were very common. Some discussed the strongintermolecular bonds in diamond. Few candidates seemed to be aware thatdifferent types of bond were broken in diamond and hydrogen.
The majority of candidates identified a property of graphite but explanationswere often inadequate or confused. Many gave the presence of free electronsbetween the layers as the reason for its soft/slippery property. To gain theexplanation mark for electrical conductivity, reference to free moving, mobile ordelocalised electrons was required.
The bonding in oxygen was very well answered with most candidates gainingboth marks. Some lost a mark for having the incorrect number of non-bondingelectrons in the outer shell. Candidates who failed to gain any marks usuallygave the bonding for chlorine.
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The structures were generally well known. However, explanations were often vague or imprecise, e.g. no
reference to movement of electrons in part (a) and use of molecules/atoms sliding over each other in (b).
This comment originally referred to question 8 on paper 4472/01 (14/01/2014)
6.
This comment originally referred to question 2 on paper 4472/01 (20/05/2013)
7. This question was not well answered and most of the candidates failed to gain both available marks.
Many incorrectly linked graphite with a metallic structure and potassium with an ionic structure.
(a)
Very well answered.(b)
This was poorly answered with many candidates naming an element rather than a compound with a
simple covalent structure. Candidates must read questions more carefully.
(c)
This comment originally referred to question 2 on paper 4472/01 (15/05/2014)
8. A very well answered question.(a)
The general term 'metal' was often given without naming a specific metal. 'Carbon' and 'hydrogen' were
other examples of unacceptable answers.
(b)
Well answered. The structure of 'sodium chloride' or 'B' was incorrectly given by some candidates.(c)
Generally well answered although a few candidates incorrectly gave 'D'.(d)
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This comment originally referred to question 1 on paper 4472/01 (14/05/2015)
9.(a)
(b)
Most candidates drew a line from metallic to high melting point and thenstruggled to find suitable properties for the remaining types of structure. Giantcovalent linked to malleable and ductile was a common error.
Generally this was well answered. Shape memory alloy and hydrogel wereoften given for the gumshield while shape memory alloy was a common choicefor disposable nappies.
(ii) Quite well answered although 'sodium oxide', 'oxygen' and 'carbon dioxide' were common incorrect
answers.
This comment originally referred to question 5 on paper 4472/02 (20/05/2013)
10. Very well answered.(a)
Very poorly answered. The commonest response was a diagram showing the electron shells of a sodium
atom. Many potentially good diagrams had no positive charge on the metal ions.
(b)
(i) Quite well answered but many incorrectly gave an 'orange/yellow flame' or hit the same marking point
twice e.g. 'fizzing and bubbles of gas'.
(c)
Well answered. A significant number of candidates, however, failed to gain the mark when they referred to
a 'more vigorous or violent reaction'.
(d)
Although many candidates gained a mark for recognising that the atoms get bigger very few gained the
second mark. Common unacceptable answers were that as you go down Group 1 'there are more
electrons', 'more electrons in the outer shell' and the 'metals become more unstable'.
(e)
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