What is inside these Atoms and Molecules notes
These notes follow the board textbook chapter “Atoms and Molecules”. Each page has one big idea, with colour cards so you can revise fast.
- Laws of chemical combination and Dalton’s atomic theory (3.1)
- What is an atom? Size, symbols and atomic mass (3.2)
- What is a molecule? Atoms, ions and atomicity (3.3)
- Writing chemical formulae and naming compounds (3.4)
- Molecular mass and the mole concept (3.5)
Also in the PDF
- Cover and chapter map: every topic with its page number, a concept diagram and what to know before you start.
- Law of conservation of mass and law of constant proportions
- n = m ÷ M and N = n × N₀, with Avogadro’s number 6.022 × 10²³
- Valency and the criss-cross method for writing formulae
- Common mistakes and tips on each topic page.
- Quick-revision page: every formula and rule of the chapter on one sheet.
- Last-day checklist with answer-writing templates and a 5-minute plan.
- Practice questions with an answer key so you can check yourself.
Preview the notes
Tap a page to enlarge it. Use “Read online” or “Download PDF” at the top for the full notes.
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Complete General Science revision notes: 152 pages with formulas, worked examples, quick-revision pages and practice questions with answers. Read the first pages free.
Practise after you revise
Atoms and Molecules: MCQs with answers
Free sample MCQs in Assamese, with an explanation for every answer. Chapter numbers on the MCQ pages follow the Leepie app and can differ from the textbook.
Practise Atoms and Molecules MCQsHow to use these notes
- Read the chapter map and the “before you start” cards.
- Study one topic page at a time, then cover the worked example and solve it yourself.
- Revise from the quick-revision page every day in the last week.
- Finish with the practice questions and check your answers against the answer key.
Frequently Asked Questions
Are these revision notes free?
Yes. Chapters 1 to 3 of each Class 9 subject are free to read online and download, with no sign-up. All chapters together are sold as one complete revision notes book in the Leepie store.
Which language are the notes in?
The notes are written in Assamese, for students of the Assam board (SEBA / ASSEB). Chapter names also carry the English name, for example “Atoms and Molecules”.
Is this an official SEBA or textbook publication?
No. Leepie’s revision notes are an independent study aid made to go with the textbook. Always read your textbook and follow your teacher’s guidance.
How should I use these notes?
Read the colour cards once, solve the worked examples yourself, then use the quick-revision page and the last-day checklist before the exam. Finish with the practice questions and check your answers.