Level 1 — Basic Recall (1–10)

1. What is an atom?

2. Name the three subatomic particles.

3. State the charge of a proton.

4. State the charge of an electron.

5. Where are neutrons located in an atom?

6. Define atomic number.

7. Define mass number.

8. What are isotopes?

9. Give an example of a pair of isotopes.

10. Who proposed the plum pudding model?

Level 2 — Understanding (11–20)

11. Explain why isotopes have similar chemical properties.

12. Describe Rutherford’s gold foil experiment.

13. What conclusion showed that the atom is mostly empty space?

14. Why do electrons not fall into the nucleus?

15. Compare protons and neutrons.

16. Why is the nucleus positively charged?

17. Define relative atomic mass.

18. Explain how electron shells are arranged.

19. Why is the mass of an electron often ignored?

20. Distinguish between atomic mass unit (amu) and mass number.

Level 3 — Application (21–30)

21. Calculate the number of neutrons in Mg-24.

22. Chlorine has isotopes Cl-35 and Cl-37. Draw their nuclear symbols.

23. A neutral atom has 11 protons; how many electrons does it have?

24. Determine the atomic number of an element with 15 protons.

25. A sample contains 80% Li-7 and 20% Li-6. Calculate Ar.

26. Explain how mass spectrometry identifies isotopes.

27. Why does removing electrons not change the element?

28. Calculate the number of subatomic particles in Ca²⁺ (mass number 40).

29. Predict how alpha particles would behave near a thick metal sheet.

30. Illustrate the electron arrangement of oxygen.

Level 4 — Analysis (31–40)

31. Why were Bohr’s improvements necessary after Rutherford?

32. Analyse why electrons must exist in quantized shells.

33. Compare the nuclear model with the plum pudding model.

34. Explain how the concept of isotopes disproved Dalton’s theory.

35. Why does atomic radius increase down a group?

36. Analyse the stability of isotopes with different neutron-proton ratios.

37. Evaluate why nuclear forces must be stronger than electrostatic repulsion.

38. Explain how the discovery of the neutron revolutionized nuclear chemistry.

39. Compare the electron cloud model with Bohr’s shell model.

40. Why do some nuclei undergo radioactive decay?

Level 5 — Exam/Challenge (41–50)

41. A sample of chlorine contains isotopes 35 (75%) and 37 (25%). Calculate Ar.

42. Predict the spectrum pattern if electrons were not quantized.

43. Explain why mass spectrometry is more accurate than relative mass calculations.

44. Compare evidence from spectroscopy vs electron-deflection experiments.

45. Discuss the limitations of Bohr’s model for multi-electron atoms.

46. Interpret the stability of isotopes using binding energy.

47. Explain how electron shielding affects atomic properties.

48. Why do heavier isotopes often have higher binding energy?

49. Predict how atomic structure affects the periodic law.

50. Describe how modern quantum models differ fundamentally from classical atomic theory.