Please check the examination details below before entering your candidate information
Candidate surname Other names
Centre Number Candidate Number
Pearson Edexcel Level 3 GCE
Monday 15 June 2026 Mark Scheme (Results)
Morning (Time: 2 hours 30 minutes) Paper
reference 9CH0/03
Chemistry
Advanced Summer 2026
PAPER 3: General and Practical Principles in Chemistry
You must have: Total Marks
Scientific calculator, Data Booklet, ruler
Instructions Pearson Edexcel Advanced Level in Chemistry
• Use black ink or ball‑point pen. 9CH0/03
• IfFillpencil is used for diagrams/sketches/graphs it must be dark (HB or B).
• centrein the boxes at the top of this page with your name,
number and candidate number.
• Answer all questions.
• Answer the questions in the spaces provided
– there may be more space than you need.
Information
• The total mark for this paper is 120.
• The marks for each question are shown in brackets
– use this as a guide as to how much time to spend on each question.
• For the question marked with an asterisk (*), marks will be awarded for your
ability to structure your answer logically, showing how the points that you make
are related or follow on from each other where appropriate.
• A Periodic Table is printed on the back cover of this paper.
Advice
• Read each question carefully before you start to answer it.
• Show all your working in calculations and include units where appropriate.
• your answers if you have time at the end.
Check
Turn over
P83918APearson Education Ltd.
P:1/1/1/1/1/1/1/1/
*P83918A0136*
, Answer ALL questions.
Edexcel and BTEC Qualifications
Write your answers in the spaces provided.
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
1 This question is about isotopes. Edexcel and BTEC qualifications are awarded by Pearson, the UK’s
(a) Explain why isotopes of the same element are distinguished by largest awarding body. We provide a wide range of qualifications
mass number and not by atomic number. including academic, vocational, occupational and specific
Refer to sub‑atomic particles in your answer. programmes for employers. For further information visit our
(2) qualifications websites at or .
................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alternatively, you can get in touch with us using the details on our
contact us page at
................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(b) Twenty isotopes of neon are known. Pearson: helping people progress, everywhere
One sample of neon contained three stable isotopes of neon with the percentage Pearson aspires to be the world’s leading learning company. Our aim is to help
abundances shown.
everyone progress in their lives through education. We believe in every kind of
learning, for all kinds of people, wherever they are in the world. We’ve been
Isotope Relative isotopic mass Percentage abundance involved in education for over 150 years, and by working across 70 countries, in
20 100 languages, we have built an international reputation for our commitment to
Ne 19.99 90.48
high standards and raising achievement through innovation in education. Find
21
Ne 20.99 0.27 out more about how we can help you and your students at:
22
Ne 21.99 9.25
Calculate the relative atomic mass of neon in this sample.
Give your answer to two decimal places.
(2)
Summer 2026
Question Paper Log Number P83918A
Publication Code 9CH0_03_2606_MS
All the material in this publication is
Pearson
2
*P83918A0236*
, State why isotopes of an element have the same chemical properties.
(2) General Marking Guidance
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
• All candidates must receive the same treatment. Examiners must mark the
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
first candidate in exactly the same way as they mark the last.
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
• Mark schemes should be applied positively. Candidates must be rewarded
for what they have shown they can do rather than penalised for omissions.
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
• Examiners should mark according to the mark scheme not according to their
(Total for Question 1 = 6 marks) perception of where the grade boundaries may lie.
• There is no ceiling on achievement. All marks on the mark scheme should be
used appropriately.
• All the marks on the mark scheme are designed to be awarded. Examiners
should always award full marks if deserved, i.e. if the answer matches the
mark scheme. Examiners should also be prepared to award zero marks if the
candidate’s response is not worthy of credit according to the mark scheme.
• Where some judgement is required, mark schemes will provide the principles
by which marks will be awarded and exemplification may be limited.
• When examiners are in doubt regarding the application of the mark scheme
to a candidate’s response, the team leader must be consulted.
• Crossed out work should be marked UNLESS the candidate has replaced it
with an alternative response.
3
*P83918A0336* Turn over
, Question Mark
Answer Additional Guidance
Number
es
1(a) An explanation that makes reference to the following Ignore reference to electrons (2)
2 This question is about atomic orbitals, subshells, quantum shells and points:
electronic configurations.
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
(a) Draw the shape of a single p‑orbital, labelling the position of the nucleus. • mass number includes the number of neutrons, (1)
(1) which is different for isotopes
• (whereas) atomic number is the number of (1)
protons, and isotopes have the same number of
protons If no other mark awarded allow one mark for isotopes have the same
number of protons but different numbers of neutrons
ad
Question Mark
Answer Additional Guidance
Number
1(b) Example of calculation (2)
• correct expression for calculation of Ar (1) Ar = ((19.99 × 90.48) + (20.99 × 0.27) + (21.99 × 9.25))
(b) Determine how many more electrons are needed to fill a d‑subshell than 100
a p‑subshell. Ar = (20.1777)
(1)
• relative atomic mass to 2 dp (1) Ar = 20.18
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TE on correct calculation from transposed numbers
Part of the atomic emission spectrum of hydrogen is shown. Ignore units of g mol−1 / AMU but penalise any other units
Correct answer without working scores (2)
gr
20.2 without working scores 0
2.4 2.6 2.8 3.0 3.2
Frequency / 1015 Hz
This shows the frequencies of the radiation emitted when excited electrons return
to the ground state.
Explain how this part of the spectrum provides evidence for the existence of
quantum shells.
(2)
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
t
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
es
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
*P83918A0436*
Candidate surname Other names
Centre Number Candidate Number
Pearson Edexcel Level 3 GCE
Monday 15 June 2026 Mark Scheme (Results)
Morning (Time: 2 hours 30 minutes) Paper
reference 9CH0/03
Chemistry
Advanced Summer 2026
PAPER 3: General and Practical Principles in Chemistry
You must have: Total Marks
Scientific calculator, Data Booklet, ruler
Instructions Pearson Edexcel Advanced Level in Chemistry
• Use black ink or ball‑point pen. 9CH0/03
• IfFillpencil is used for diagrams/sketches/graphs it must be dark (HB or B).
• centrein the boxes at the top of this page with your name,
number and candidate number.
• Answer all questions.
• Answer the questions in the spaces provided
– there may be more space than you need.
Information
• The total mark for this paper is 120.
• The marks for each question are shown in brackets
– use this as a guide as to how much time to spend on each question.
• For the question marked with an asterisk (*), marks will be awarded for your
ability to structure your answer logically, showing how the points that you make
are related or follow on from each other where appropriate.
• A Periodic Table is printed on the back cover of this paper.
Advice
• Read each question carefully before you start to answer it.
• Show all your working in calculations and include units where appropriate.
• your answers if you have time at the end.
Check
Turn over
P83918APearson Education Ltd.
P:1/1/1/1/1/1/1/1/
*P83918A0136*
, Answer ALL questions.
Edexcel and BTEC Qualifications
Write your answers in the spaces provided.
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
1 This question is about isotopes. Edexcel and BTEC qualifications are awarded by Pearson, the UK’s
(a) Explain why isotopes of the same element are distinguished by largest awarding body. We provide a wide range of qualifications
mass number and not by atomic number. including academic, vocational, occupational and specific
Refer to sub‑atomic particles in your answer. programmes for employers. For further information visit our
(2) qualifications websites at or .
................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alternatively, you can get in touch with us using the details on our
contact us page at
................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(b) Twenty isotopes of neon are known. Pearson: helping people progress, everywhere
One sample of neon contained three stable isotopes of neon with the percentage Pearson aspires to be the world’s leading learning company. Our aim is to help
abundances shown.
everyone progress in their lives through education. We believe in every kind of
learning, for all kinds of people, wherever they are in the world. We’ve been
Isotope Relative isotopic mass Percentage abundance involved in education for over 150 years, and by working across 70 countries, in
20 100 languages, we have built an international reputation for our commitment to
Ne 19.99 90.48
high standards and raising achievement through innovation in education. Find
21
Ne 20.99 0.27 out more about how we can help you and your students at:
22
Ne 21.99 9.25
Calculate the relative atomic mass of neon in this sample.
Give your answer to two decimal places.
(2)
Summer 2026
Question Paper Log Number P83918A
Publication Code 9CH0_03_2606_MS
All the material in this publication is
Pearson
2
*P83918A0236*
, State why isotopes of an element have the same chemical properties.
(2) General Marking Guidance
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
• All candidates must receive the same treatment. Examiners must mark the
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
first candidate in exactly the same way as they mark the last.
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
• Mark schemes should be applied positively. Candidates must be rewarded
for what they have shown they can do rather than penalised for omissions.
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
• Examiners should mark according to the mark scheme not according to their
(Total for Question 1 = 6 marks) perception of where the grade boundaries may lie.
• There is no ceiling on achievement. All marks on the mark scheme should be
used appropriately.
• All the marks on the mark scheme are designed to be awarded. Examiners
should always award full marks if deserved, i.e. if the answer matches the
mark scheme. Examiners should also be prepared to award zero marks if the
candidate’s response is not worthy of credit according to the mark scheme.
• Where some judgement is required, mark schemes will provide the principles
by which marks will be awarded and exemplification may be limited.
• When examiners are in doubt regarding the application of the mark scheme
to a candidate’s response, the team leader must be consulted.
• Crossed out work should be marked UNLESS the candidate has replaced it
with an alternative response.
3
*P83918A0336* Turn over
, Question Mark
Answer Additional Guidance
Number
es
1(a) An explanation that makes reference to the following Ignore reference to electrons (2)
2 This question is about atomic orbitals, subshells, quantum shells and points:
electronic configurations.
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
(a) Draw the shape of a single p‑orbital, labelling the position of the nucleus. • mass number includes the number of neutrons, (1)
(1) which is different for isotopes
• (whereas) atomic number is the number of (1)
protons, and isotopes have the same number of
protons If no other mark awarded allow one mark for isotopes have the same
number of protons but different numbers of neutrons
ad
Question Mark
Answer Additional Guidance
Number
1(b) Example of calculation (2)
• correct expression for calculation of Ar (1) Ar = ((19.99 × 90.48) + (20.99 × 0.27) + (21.99 × 9.25))
(b) Determine how many more electrons are needed to fill a d‑subshell than 100
a p‑subshell. Ar = (20.1777)
(1)
• relative atomic mass to 2 dp (1) Ar = 20.18
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TE on correct calculation from transposed numbers
Part of the atomic emission spectrum of hydrogen is shown. Ignore units of g mol−1 / AMU but penalise any other units
Correct answer without working scores (2)
gr
20.2 without working scores 0
2.4 2.6 2.8 3.0 3.2
Frequency / 1015 Hz
This shows the frequencies of the radiation emitted when excited electrons return
to the ground state.
Explain how this part of the spectrum provides evidence for the existence of
quantum shells.
(2)
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
t
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
es
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................................................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
*P83918A0436*
