OCR Gateway Science Chemistry A (J248)
GCSE Chemistry
Unit worksheet
Unit 1 worksheet — C1 Particles
Original exam-style worksheet — not an official exam paper
Time guide: 50–60 minutes · Questions: 32 · Total marks: 104
Written in OCR Gateway A style. Use the data sheet for relative atomic masses if needed.
Answer all questions. Show working. Answers are in a separate file on the Worksheets page — do not look at them until you have finished.
1. State what is meant by an atom. [1]
2. State what is meant by a proton. [1]
3. State what is meant by a neutron. [1]
4. State what is meant by an electron. [1]
5. State what is meant by an isotope. [1]
6. State what is meant by the periodic table. [1]
7. State what is meant by a Group 1 metal. [1]
8. State what is meant by a Group 7 element. [1]
9. State what is meant by a mixture. [1]
10. State what is meant by a compound. [1]
11. Grace is asked about an atom in a OCR Chemistry paper.
(a) Describe an atom. [2]
(b) Explain why an atom is important in this topic. [3]
12. Grace is asked about a proton in a OCR Chemistry paper.
(a) Describe a proton. [2]
(b) Explain why a proton is important in this topic. [3]
13. Grace is asked about a neutron in a OCR Chemistry paper.
(a) Describe a neutron. [2]
(b) Explain why a neutron is important in this topic. [3]
14. Grace is asked about an electron in a OCR Chemistry paper.
(a) Describe an electron. [2]
(b) Explain why an electron is important in this topic. [3]
15. Grace is asked about an isotope in a OCR Chemistry paper.
(a) Describe an isotope. [2]
(b) Explain why an isotope is important in this topic. [3]
16. Grace is asked about the periodic table in a OCR Chemistry paper.
(a) Describe the periodic table. [2]
(b) Explain why the periodic table is important in this topic. [3]
17. An atom has 13 protons and 25 neutrons. Write the mass number and atomic number. [3]
18. Calculate the relative atomic mass of an element with 75% isotope 35 and 25% isotope 37. [3]
19. How many electrons are in a 13+ ion of this element if it is in Group 1? [3]
20. A shell holds 2n² electrons. How many in the 3rd shell? [3]
21. 16 g of carbon-12 contains 1 mole. How many atoms? [3]
22. Write the electronic structure of an element with 17 electrons. [3]
23. Grace carries out the flame-test practical for metal ions. This is a typical OCR required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
24. Grace carries out paper chromatography of inks. This is a typical OCR required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
25. Grace carries out separating rock salt (sand and salt). This is a typical OCR required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
26. Grace carries out investigating the reaction of Group 1 metals with water (demonstration). This is a typical OCR required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
27. Compare an element with a compound. [4]
28. Compare Group 1 with Group 7. [4]
29. Compare a mixture with a compound. [4]
30. Compare the plum-pudding model with the nuclear model. [4]
31. Apply your knowledge of a Group 1 metal to this situation: outer electron is further / more shielding [3]
32. Apply your knowledge of a Group 7 element to this situation: chlorine is more reactive [3]