Chemistry

Atoms and Molecules


Molecules


A molecule is an electrically neutral group of two (or more) atoms chemically bonded together.The forces which hold the atoms together in a molecule are called covalent bonds.Thus, a combination of atoms is called a molecule.We know that atoms of most of the elements are very reactive and cannot exist in the free state (as single atoms).This is not so with molecules.Molecules can exist in free state because they are very stable.This gives us another definition of molecule which can be written as follows:A molecule is the smallest particle of a substance (element or compound) which has the properties of that substance and can exist in the free state.
Molecules can be formed either by the combination of atoms of the 'same element' or of 'different elements'.Depending on this, there are two types of molecules : molecules of elements,and molecules of compounds.This is discussed below.

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Notes
Atoms and Molecules - Notes
1. Drawbacks of Dalton’s Atomic Theory
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2. Monovalent Cations (Cations Having a Valency of 1+)
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3. Dalton’s Symbols of Elements
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4. Divalent Cations (Cations Having a Valency of 2+)
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5. Trivalent Cations (Cations Having a Valency of 3+)
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6. Formulae of Some Molecular Compounds
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7. An Important Discussion
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8. Molecular Formulae of Some Common Elements
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9. an example, let us give the significance of symbol C
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10. 2. A Negatively Charged Ion is Known as Anion
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11. As an example, let us give the significance of the formula H2O
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12. Molecules
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13. Chemical Formulae
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14. Molecular Mass
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15. Molecules of Compounds
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16. Atoms, Molecules and Ions
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17. Explanation of the Law of Conservation of Mass
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18. Some Ionic Compounds
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19. Atoms
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20. Mole of Molecules
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21. Formula Mass
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22. 1. A Positively Charged Ion is Known as Cation
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23. Formulae of Elements
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24. 1. Molecules of Elements
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25. Simple Ions and Compound Ions (Polyatomic Ions)
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26. Symbols of Elements
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27. Gram Atomic Mass And Gram Molecular Mass
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28. John Dalton
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29. Mole of Atoms
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30. Formulae of Compounds
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31. Ions
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32. Explanation of the Law of Constant Proportions
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33. Dalton's Atomic Theory
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34. Significance of the Formula of a Substance
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35. Some Common Ions
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36. Molecular Masses of Some Common Elements
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37. Ionic Compounds
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38. Laws Of Chemical Combination
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39. Calculation of Molecular Mass
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40. Formula Unit of Ionic Compounds
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41. Divalent Anions (Anions Having a Valency of 2-)
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42. How Do Atoms Exist
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43. Atoms And Molecules
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44. Problems Based On Moles Of Molecules
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45. Writing Of Formulae Of Ionic Compounds
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46. Experiment to Verify Law of Conservation of Mass
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47. Gram Molecular Mass
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48. Gram Atomic Mass
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49. Laws Of Conservation of Mass
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50. Atomic Radii of Some Common Elements
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