Chemistry

Atoms and Molecules


Atomic Masses of Some Common Elements


ElementSymbolAtomic massElementSymbolAtomic mass
1.Hydrogen
2.Carbon
3.Nitrogen
4.Oxygen
5.Sodium
6.Magnesium
7.Aluminium
H
C
N
O
Na
Mg
A1
1 u
12 u
14 u
16 u
23 u
24 u
27 u
8.Phosphorus
9.Sulphur
10.Chlorine
11.Potassium
12.Calcium
13.Iron
14.Copper
p
s
Cl
K
Ca
Fe
Cu
31 u
32 u
35.5 u
39 u
40 u
56 u
63.5 u

It has been found by experiments that the mass of a carbon-12 atom is 1.9926 x 10-23 gram. If we divide this mass by 12, we will get the absolute mass of the atomic mass unit (u). It comes to be 1.6605 x 10-24 gram. This means that the actual mass of the atomic mass unit is 1.6605 x 10-24 gram.
That is, 1 u = 1.6605 x 10-24g
By using this value of atomic mass unit,we can find the actual mass(or absolute mass) of the atom of any element.Before we end this discussion,it will be good to note the significance of the chemical symbol of an element which is given 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. 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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5. Dalton’s Symbols of Elements
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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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8. An Important Discussion
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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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12. Molecules
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13. As an example, let us give the significance of the formula H2O
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14. Simple Ions and Compound Ions (Polyatomic Ions)
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15. Molecules of Compounds
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16. Formulae of Elements
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17. Chemical Formulae
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18. Some Ionic Compounds
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19. Symbols of Elements
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20. Molecular Mass
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21. Gram Atomic Mass And Gram Molecular Mass
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22. Atoms
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23. Formulae of Compounds
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24. Formula Mass
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25. Atoms, Molecules and Ions
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26. 1. Molecules of Elements
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27. Mole of Atoms
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28. 1. A Positively Charged Ion is Known as Cation
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29. Ions
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30. Mole of Molecules
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31. Dalton's Atomic Theory
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32. Laws Of Chemical Combination
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33. Calculation of Molecular Mass
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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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36. Some Common Ions
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37. Explanation of the Law of Constant Proportions
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38. John Dalton
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39. Significance of the Formula of a Substance
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40. Formula Unit of Ionic Compounds
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41. Ionic Compounds
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42. Symbols Derived from Latin Names of the Elements
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43. Modern Symbols of Elements
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44. Atomic Mass Of An Element
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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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48. Laws Of Conservation of Mass
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49. Problems Based On Moles Of Atoms
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50. Writing Of Formulae Of Ionic Compounds
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