Atoms And Molecules
Sugar, salt, sand, diamond, graphite, copper, silver, gold, iron, aluminium, wood, rocks, minerals,food and fabrics (clothes) are all different kinds of matter. Matter is called padarth in Hindi. An Indian philosopher, Maharishi Kanad, said that if we go on dividing matter (padarth), we will get smaller and smaller particles of matter. Ultimately, we will get the smallest particle of matter, which cannot be divided any further. Based on this philosophy, Kanad was one of the first persons to propose that matter (or padarth ) is made up of very small particles called 'parmanu'. John Dalton called these particles by the name of atom. The word 'atom' means 'indivisible'— something which cannot be divided further.
Another Indian philosopher Pakudha Katyayama went a step further and proposed that the particles of matter (atoms or parmanu) normally exist in a combined form and various combinations of particles give us various kinds of matter. This combined form of atoms is now called 'molecules'. We now know that all matter is made up of small particles called atoms and molecules. Different kinds of atoms and molecules have different properties due to which different kinds of matter also show different properties. Thus, the properties of matter depend on the properties of atoms and molecules from which it is made.
We will now describe the laws of chemical combination (established by experiments) which confirmed the idea of atoms being the smallest particles of matter.
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Atoms and Molecules - Notes
2. Monovalent Cations (Cations Having a Valency of 1+)
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3. Divalent Cations (Cations Having a Valency of 2+)
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4. Trivalent Cations (Cations Having a Valency of 3+)
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6. an example, let us give the significance of symbol C
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7. Formulae of Some Molecular Compounds
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9. Explanation of the Law of Conservation of Mass
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10. Molecular Formulae of Some Common Elements
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11. 2. A Negatively Charged Ion is Known as Anion
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13. As an example, let us give the significance of the formula H
2O
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14. Simple Ions and Compound Ions (Polyatomic Ions)
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21. Gram Atomic Mass And Gram Molecular Mass
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28. 1. A Positively Charged Ion is Known as Cation
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34. Divalent Anions (Anions Having a Valency of 2-)
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35. Molecular Masses of Some Common Elements
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37. Explanation of the Law of Constant Proportions
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39. Significance of the Formula of a Substance
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42. Symbols Derived from Latin Names of the Elements
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45. Valencies of Some Common Metal Elements Valencies of Some Common Non-Metal Elements
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46. Atomic Masses of Some Common Elements
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47. Writing Of Formulae Of Molecular Compounds
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50. Writing Of Formulae Of Ionic Compounds
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