Centre Number
Candidate Number
General Certificate of Secondary Education
2025
GCSE Chemistry
Unit 1
Higher Tier
*GCM12*
[GCM12] *GCM12*
MONDAY 19 MAY, MORNING
TIME
1 hour 15 minutes.
INSTRUCTIONS TO CANDIDATES
Write your Centre Number and Candidate Number in the spaces provided at the top of this
page.
You must answer the questions in the spaces provided.
Do not write outside the boxed area on each page or on blank pages.
Complete questions in black ink and use a dark HB pencil for drawings and graphs.
Do not write with a gel pen.
Answer all five questions.
INFORMATION FOR CANDIDATES
The total mark for this paper is 80.
Figures in brackets printed down the right-hand side of pages indicate the marks awarded
to each question or part question.
You may use a scientific calculator.
Quality of written communication will be assessed in Question 2(b).
A Data Leaflet, which includes a Periodic Table of the Elements, is included in this question
paper.
14542
*20GCM1201*
*20GCM1201*
, 1 Magnesium reacts with oxygen to form magnesium oxide.
(a) Write a balanced symbol equation for this reaction.
[3]
(b) The table below shows some properties of magnesium, oxygen and
magnesium oxide.
Physical property Magnesium Oxygen Magnesium oxide
Melting point /°C 650 -218 2852
Boiling point /°C 1090 -183 3600
State at room
solid gas
temperature (25°C)
Colour at room
grey colourless
temperature (25°C)
Structure giant lattice
Bonding covalent ionic
(i) Complete the table above. [5]
(ii) Complete the following for a molecule of oxygen.
Total number of electrons:
Number of lone pairs of electrons:
Number of electrons in covalent bonds: [3]
(iii) Explain why oxygen has a low boiling point.
[2]
14542
*20GCM1202*
*20GCM1202*
, (iv) Explain what is meant by ionic bonding.
[1]
(v) Complete the dot and cross diagram below by drawing the electronic
configurations of the ions formed and write the formulae of the ions.
magnesium atom oxygen atom
magnesium ion oxide ion
Formula Formula [4]
[Turn over
14542
*20GCM1203*
*20GCM1203*
Candidate Number
General Certificate of Secondary Education
2025
GCSE Chemistry
Unit 1
Higher Tier
*GCM12*
[GCM12] *GCM12*
MONDAY 19 MAY, MORNING
TIME
1 hour 15 minutes.
INSTRUCTIONS TO CANDIDATES
Write your Centre Number and Candidate Number in the spaces provided at the top of this
page.
You must answer the questions in the spaces provided.
Do not write outside the boxed area on each page or on blank pages.
Complete questions in black ink and use a dark HB pencil for drawings and graphs.
Do not write with a gel pen.
Answer all five questions.
INFORMATION FOR CANDIDATES
The total mark for this paper is 80.
Figures in brackets printed down the right-hand side of pages indicate the marks awarded
to each question or part question.
You may use a scientific calculator.
Quality of written communication will be assessed in Question 2(b).
A Data Leaflet, which includes a Periodic Table of the Elements, is included in this question
paper.
14542
*20GCM1201*
*20GCM1201*
, 1 Magnesium reacts with oxygen to form magnesium oxide.
(a) Write a balanced symbol equation for this reaction.
[3]
(b) The table below shows some properties of magnesium, oxygen and
magnesium oxide.
Physical property Magnesium Oxygen Magnesium oxide
Melting point /°C 650 -218 2852
Boiling point /°C 1090 -183 3600
State at room
solid gas
temperature (25°C)
Colour at room
grey colourless
temperature (25°C)
Structure giant lattice
Bonding covalent ionic
(i) Complete the table above. [5]
(ii) Complete the following for a molecule of oxygen.
Total number of electrons:
Number of lone pairs of electrons:
Number of electrons in covalent bonds: [3]
(iii) Explain why oxygen has a low boiling point.
[2]
14542
*20GCM1202*
*20GCM1202*
, (iv) Explain what is meant by ionic bonding.
[1]
(v) Complete the dot and cross diagram below by drawing the electronic
configurations of the ions formed and write the formulae of the ions.
magnesium atom oxygen atom
magnesium ion oxide ion
Formula Formula [4]
[Turn over
14542
*20GCM1203*
*20GCM1203*
