AS-Level EDEXCEL 2025 Chemistry PAPER 1 Mark Scheme
Mark Scheme (Results)
Summer 2025
Pearson Edexcel Level GCE Advance Subsidiary In Chemistry (8CH0)
Paper 01: Core Inorganic and Physical 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
Answer Mark
Number
1(a) The only correct answer is B (a pair of electrons from a covalent bond) (1)
A is not correct because electronegativity is defined as attracting a pair of electrons
C is not correct because electronegativity refers to the attracting of electrons from a covalent bond not an atom
D is not correct because electronegativity is defined as attracting the electrons from a covalent bond
Question
Answer Additional Guidance Mark
Number
1(b) An answer that makes reference to the following Example of diagram (2)
points:
four bonding pairs of electrons and no lone Cl Cl
pairs on the central silicon atom (1)
×
×
3 lone pairs of electrons on each chlorine Cl × Si Cl Cl × Si Cl
atom (1)
×
×
Cl Cl
Allow dots and crosses reversed
Allow any symbols for electrons as long as two different
symbols, one for chlorine and one for silicon
All electrons the same scores M2 only
Mark Scheme (Results)
Summer 2025
Pearson Edexcel Level GCE Advance Subsidiary In Chemistry (8CH0)
Paper 01: Core Inorganic and Physical 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
Answer Mark
Number
1(a) The only correct answer is B (a pair of electrons from a covalent bond) (1)
A is not correct because electronegativity is defined as attracting a pair of electrons
C is not correct because electronegativity refers to the attracting of electrons from a covalent bond not an atom
D is not correct because electronegativity is defined as attracting the electrons from a covalent bond
Question
Answer Additional Guidance Mark
Number
1(b) An answer that makes reference to the following Example of diagram (2)
points:
four bonding pairs of electrons and no lone Cl Cl
pairs on the central silicon atom (1)
×
×
3 lone pairs of electrons on each chlorine Cl × Si Cl Cl × Si Cl
atom (1)
×
×
Cl Cl
Allow dots and crosses reversed
Allow any symbols for electrons as long as two different
symbols, one for chlorine and one for silicon
All electrons the same scores M2 only
