About Atoms, bonding and structure in O Level Chemistry
Atoms, bonding and structure is one of the 12 main topics in our O Level Chemistry (Cambridge (CAIE) 5070) question bank, and about 11% of its real questions come from it. Tayyari Karo has 71 real questions on this topic from 2021 to 2026, from Paper 1, Paper 2; 63 are multiple choice and marked instantly, and the rest are structured questions with a model answer. By difficulty: 63 medium, 7 easy, 1 hard.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
Try 6 real questions
These are real past-paper questions. Think of your answer first, then open the explanation.
May/June 2026 · Paper 1 · Atoms, bonding and structure
The difference between the nucleon number and the proton number indicates the number of ......1...... in the atom. Atoms that have different nucleon numbers but the same proton number are called ......2...... .
Which words correctly complete gaps 1 and 2?
- 1 electrons, 2 isomers
- 1 electrons, 2 isotopes
- 1 neutrons, 2 isomers
- 1 neutrons, 2 isotopes
Show answer and explanation
Answer: D. 1 neutrons, 2 isotopes
Nucleon number − proton number = number of neutrons; atoms of the same element with different numbers of neutrons are isotopes.
Oct/Nov 2025 · Paper 1 · Atoms, bonding and structure
The structure of hydroxylamine, NH2OH, is a nitrogen atom bonded to two hydrogen atoms and to an oxygen atom, with the oxygen atom also bonded to a third hydrogen atom (H2N-OH). Which row about hydroxylamine is correct?
- total electrons in the molecule 14; electrons in the bonds of the molecule 8
- total electrons in the molecule 14; electrons in the bonds of the molecule 6
- total electrons in the molecule 18; electrons in the bonds of the molecule 8
- total electrons in the molecule 18; electrons in the bonds of the molecule 6
Show answer and explanation
Answer: C. total electrons in the molecule 18; electrons in the bonds of the molecule 8
NH2OH has 18 electrons in total (7 from N, 8 from O and 1 from each of three H atoms), and its four covalent bonds (two N-H, one N-O and one O-H) contain 8 electrons.
May/June 2024 · Paper 1 · Atoms, bonding and structure
Covalent bond =
- shared electron pair
- transfer of electrons
- delocalised electrons
- proton transfer
Show answer and explanation
Answer: A. shared electron pair
Shared pair.
May/June 2023 · Paper 1 · Atoms, bonding and structure
Electrons in Cl⁻? (Cl proton 17)
- 17
- 18
- 19
- 20
Show answer and explanation
Answer: B. 18
17 + 1 = 18.
May/June 2022 · Paper 1 · Atoms, bonding and structure
Which is ionic and conducts when molten?
- diamond
- sodium chloride
- water
- oxygen
Show answer and explanation
Answer: B. sodium chloride
NaCl ionic, conducts molten.
Oct/Nov 2022 · Paper 1 · Atoms, bonding and structure
Ionic compounds have high melting points because
- weak forces
- strong electrostatic forces between ions
- covalent bonds
- delocalised electrons
Show answer and explanation
Answer: B. strong electrostatic forces between ions
Strong ionic attractions.
