IB Chemistry HL · 2025
Unit 1: Structure 1: Models of the particulate nature of matter
121 past paper questions from 11 papers across 3 exam sessions. See what repeats, then practise the same skills with AI marking.
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HL archive · 2025 to 2026
Unit 1: Structure 1: Models of the particulate nature of matter
Latest exam session: May 2026
- questions
- 121
- questions
- papers
- 11
- papers
- exam sessions
- 3
- exam sessions
- micro-topics
- 15
Topics in Unit 1: Structure 1: Models of the particulate nature of matter
In syllabus order. The ring is the share of the marks each one carries.
1.1
Introduction to the particulate nature of matter
29% of marks54 of the 184 marks across the 11 Chemistry HL papers analysed (29%) were on this topic. A past-paper pattern, not a guarantee for your next paper. · 33 questions
1.2
The nuclear atom
7% of marks13 of the 184 marks across the 11 Chemistry HL papers analysed (7%) were on this topic. A past-paper pattern, not a guarantee for your next paper. · 10 questions
1.3
Electron configurations
15% of marks27 of the 184 marks across the 11 Chemistry HL papers analysed (15%) were on this topic. A past-paper pattern, not a guarantee for your next paper. · 20 questions
1.4
Counting particles by mass: the mole
42% of marks78 of the 184 marks across the 11 Chemistry HL papers analysed (42%) were on this topic. A past-paper pattern, not a guarantee for your next paper. · 50 questions
1.5
Ideal gases
7% of marks12 of the 184 marks across the 11 Chemistry HL papers analysed (7%) were on this topic. A past-paper pattern, not a guarantee for your next paper. · 8 questions
Exam pattern
How often each micro-topic has been examined, year by year. Each label is explained under the grid.
Does it repeat?
Top 4 of 15 micro-topics for the next sitting. Numbers are questions per year.
fewermore
| Micro-topic | 2025 | 2026 |
|---|---|---|
| 10Elements, compounds and mixtures, 2025: 10 questions | 2Elements, compounds and mixtures, 2026: 2 questions | |
| 6Writing electron configurations, 2025: 6 questions | 1Writing electron configurations, 2026: 1 question | |
| 13Empirical and molecular formulas, 2025: 13 questions | 1Empirical and molecular formulas, 2026: 1 question | |
| 22Concentration of solutions, 2025: 22 questions | 6Concentration of solutions, 2026: 6 questions |
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Questions on Unit 1: Structure 1: Models of the particulate nature of matter, by exam session
Which papers asked about Unit 1: Structure 1: Models of the particulate nature of matter, and which question numbers. Open a paper to see them highlighted.
May 2026
6 questions across 1 paper
November 2025
13 questions across 4 papers
May 2025
29 questions across 6 papers
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Frequently asked questions
Short answers about this page.
Which Chemistry HL exam sessions are covered for Unit 1: Structure 1: Models of the particulate nature of matter?
3 exam sessions from 2025 to 2026, the latest May 2026. Every Paper 1 and 2 in every timezone is read and classified in full, which gives 11 papers in this archive.
Which Unit 1: Structure 1: Models of the particulate nature of matter topic comes up most?
Elements, compounds and mixtures (1.1.1): in 64% of papers, last seen May 26 P1 TZA. Usually "explain / justify", worth about 2.4 marks in a paper that includes it.
Can I see the original question and mark scheme?
No. The wording belongs to the IB. You get the citation, the marks, the command term and the skill tested, plus our own matched practice questions with worked answers and AI marking.
What do "banker", "due" and "rising" mean?
Banker: examined in at least one sitting in four and still appearing. Due: regular before, but absent for the last two exam sessions. Rising: clearly more common in the last two years. Our classification of real papers, not an IB statistic.
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