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Atoms and Molecules

NIOS · Class 10 · Science & Tech

Complete topic list for Atoms and Molecules in NIOS Class 10 Science & Tech. Key concepts, sub-topics, and what to focus on for board exams.

93 questions42 flashcards5 concepts

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An infographic comparing the ancient Indian (Maharishi Kanad, Pakudha Katyayan) and Greek (Democritus, Leucippus) philosophical ideas about the divisibility of matter and the concept of 'Parmanu' and
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4 Topics · NIOS Class 10 Science & Tech

Topics in Atoms and Molecules

1

1. Laws of Chemical Combination

  • The law of conservation of mass states that in every chemical reaction, total mass of reactants is equal to total mass of products.
  • Lavoisier proved this law using a chemical balance in an experiment involving mercury and oxygen.
  • When mercury was heated in air, mercury (II) oxide formed and the gas left behind did not support combustion or life; it was nitrogen.
2

2. Dalton’s Atomic Theory and Atom

  • John Dalton arranged earlier atomic ideas into a scientific theory and published it in 1803.
  • Dalton's atomic theory explained the laws of conservation of mass and constant proportions.
  • Dalton’s first postulate states that matter consists of indivisible atoms.
3

3. Size, Mass, Atomic Number, and Isotopes

  • Atoms are extremely small and cannot be seen with the naked eye.
  • Nanometer is used to express atomic size, and 1 nm = 10^-9 m.
  • One teaspoon of water contains about three times as many atoms as the Atlantic ocean contains teaspoons of water.
4

4. Molecule, Molecular Mass, and Formula Mass

  • A molecule is the smallest particle of an element or compound that can exist freely under ordinary conditions.
  • A molecule is an aggregate of two or more atoms held together by chemical bonds.
  • Oxygen molecule O2 is diatomic.

Key Concepts

Central concept: Matter is made of atoms and molecules, and their laws, masses, mole concept, and formula writing explain how substances combine and behave chemically.

Ideas about divisibility of matterLaws of chemical combinationDalton's atomic theoryAtomAtomic mass and isotopesMoleculeMolecular mass and formula massMole concept

Frequently Asked Questions

What are the important topics in Atoms and Molecules for NIOS Class 10 Science & Tech?
Key topics in Atoms and Molecules include Atoms and Molecules Concept Map, Atoms and Molecules - Chapter Overview, Atoms and Molecules - Complete Chapter Overview. These are the concepts NIOS Class 10 examiners draw on most — study them first, then practise related questions.
How to score full marks in Atoms and Molecules — NIOS Class 10 Science & Tech?
Understand the core concepts first, then work through the 93 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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