A-Level EDEXCEL 2025 Chemistry PAPER 3
Mark Scheme
Mark Scheme (Results) Summer 2025
Pearson Edexcel GCE A Level In Chemistry (9CH0) Paper 03: General and Practical
Principles in Chemistry
Using the Mark Scheme
Examiners should look for qualities to reward rather than faults to penalise. This does NOT mean giving credit for incorrect or inadequate answers, but it does
mean allowing candidates to be rewarded for answers showing correct application of principles and knowledge. Examiners should therefore read carefully and
consider every response: even if it is not what is expected it may be worthy of credit.
The mark scheme gives examiners:
an idea of the types of response expected
how individual marks are to be awarded
the total mark for each question
examples of responses that should NOT receive credit.
/ means that the responses are alternatives and either answer should receive full credit.
( ) means that a phrase/word is not essential for the award of the mark, but helps the examiner to get the sense of the expected answer.
Phrases/words in bold indicate that the meaning of the phrase or the actual word is essential to the answer.
ecf/TE/cq (error carried forward) means that a wrong answer given in an earlier part of a question is used correctly in answer to a later part of the same question.
Candidates must make their meaning clear to the examiner to gain the mark. Make sure that the answer makes sense. Do not give credit for correct
words/phrases which are put together in a meaningless manner. Answers must be in the correct context.
,Quality of Written Communication
Questions which involve the writing of continuous prose will expect candidates to:
write legibly, with accurate use of spelling, grammar and punctuation in order to make the meaning clear
select and use a form and style of writing appropriate to purpose and to complex subject matter
organise information clearly and coherently, using specialist vocabulary when appropriate. Full marks will
be awarded if the candidate has demonstrated the above abilities.
Questions where QWC is likely to be particularly important are indicated (QWC) in the mark scheme, but this does not preclude others.
, Question
Number Answer Additional Guidance Mark
1(a) An answer that makes reference to the following points: (2)
energy (required) to remove / lose 1 (1) Allow e(−) for electron
electron / first electron / last electron from
an / each atom (of an element)
in 1 mol (e) of gaseous atoms (to form 1 mol (1)
of positive ions)
1 mol(e) must be referenced in either M1 or M2
to score both marks
e.g. ‘energy to remove 1 mol of electrons from
gaseous atoms’ scores 2 marks
Correct example symbol or generic equation, for
first IE, including state symbols scores 1 mark
e.g. X(g) → X+(g) + e(–) / X(g) – e(–) → X+(g)
Ignore references to standard conditions /
standard states
, Question
Number Answer Additional Guidance Mark
1(b) An explanation that makes reference to the following points: Allow there is a very large increase in 2nd IE (2)
as there is a large difference / large increase / (1)
(large) jump / in ionisation energy between first and
second ionisation energy / after first ionisation energy /
before second ionisation energy Allow alkali metal
Group 1 (1) M2 dependent on M1
Ignore reference to the subshell / orbital of the
(outer) electron even if incorrect
Mark Scheme
Mark Scheme (Results) Summer 2025
Pearson Edexcel GCE A Level In Chemistry (9CH0) Paper 03: General and Practical
Principles in Chemistry
Using the Mark Scheme
Examiners should look for qualities to reward rather than faults to penalise. This does NOT mean giving credit for incorrect or inadequate answers, but it does
mean allowing candidates to be rewarded for answers showing correct application of principles and knowledge. Examiners should therefore read carefully and
consider every response: even if it is not what is expected it may be worthy of credit.
The mark scheme gives examiners:
an idea of the types of response expected
how individual marks are to be awarded
the total mark for each question
examples of responses that should NOT receive credit.
/ means that the responses are alternatives and either answer should receive full credit.
( ) means that a phrase/word is not essential for the award of the mark, but helps the examiner to get the sense of the expected answer.
Phrases/words in bold indicate that the meaning of the phrase or the actual word is essential to the answer.
ecf/TE/cq (error carried forward) means that a wrong answer given in an earlier part of a question is used correctly in answer to a later part of the same question.
Candidates must make their meaning clear to the examiner to gain the mark. Make sure that the answer makes sense. Do not give credit for correct
words/phrases which are put together in a meaningless manner. Answers must be in the correct context.
,Quality of Written Communication
Questions which involve the writing of continuous prose will expect candidates to:
write legibly, with accurate use of spelling, grammar and punctuation in order to make the meaning clear
select and use a form and style of writing appropriate to purpose and to complex subject matter
organise information clearly and coherently, using specialist vocabulary when appropriate. Full marks will
be awarded if the candidate has demonstrated the above abilities.
Questions where QWC is likely to be particularly important are indicated (QWC) in the mark scheme, but this does not preclude others.
, Question
Number Answer Additional Guidance Mark
1(a) An answer that makes reference to the following points: (2)
energy (required) to remove / lose 1 (1) Allow e(−) for electron
electron / first electron / last electron from
an / each atom (of an element)
in 1 mol (e) of gaseous atoms (to form 1 mol (1)
of positive ions)
1 mol(e) must be referenced in either M1 or M2
to score both marks
e.g. ‘energy to remove 1 mol of electrons from
gaseous atoms’ scores 2 marks
Correct example symbol or generic equation, for
first IE, including state symbols scores 1 mark
e.g. X(g) → X+(g) + e(–) / X(g) – e(–) → X+(g)
Ignore references to standard conditions /
standard states
, Question
Number Answer Additional Guidance Mark
1(b) An explanation that makes reference to the following points: Allow there is a very large increase in 2nd IE (2)
as there is a large difference / large increase / (1)
(large) jump / in ionisation energy between first and
second ionisation energy / after first ionisation energy /
before second ionisation energy Allow alkali metal
Group 1 (1) M2 dependent on M1
Ignore reference to the subshell / orbital of the
(outer) electron even if incorrect
