How Do Atoms Exist
The atoms of only a few elements called noble gases (such as helium neon, argon and krypton, etc.) are chemically unreactive and exist in the free state (as single atoms).Atoms of most of the elements are chemically very reactive and do not exist in the free state (as single atoms).Atoms usually exist in two ways :
1.in the form of molecules,and
2.in the form of ions.
When atoms form molecules or ions, they become stable (because in doing so they acquire the stable electron arrangements of noble gases). The molecules and ions stick together in large numbers to form the various types of matter around us. Though we cannot see the individual molecules or ions with our eyes,we can, however, see the various substances which are a big collection of molecules or ions. For example,we cannot see the individual iodine molecules with our eyes because they are very,very small but we can see iodine crystal as a violet coloured solid because it is a collection of millions and millions of iodine molecules held together. Similarly, we cannot see the individual sodium ions and chloride ions () but we can see the sodium chloride compound (common salt) as a white powder because it is formed by the collection of millions and millions of sodium ions and chloride ions.We will now discuss the molecules and ions in detail,one by one.
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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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8. Formulae of Some Molecular Compounds
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9. Molecular Formulae of Some Common Elements
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10. 2. A Negatively Charged Ion is Known as Anion
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11. Explanation of the Law of Conservation of Mass
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13. As an example, let us give the significance of the formula H
2O
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15. 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. Molecular Masses of Some Common Elements
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36. Divalent Anions (Anions Having a Valency of 2-)
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38. Significance of the Formula of a Substance
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39. Explanation of the Law of Constant Proportions
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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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