Chemistry

Structure of the Atom


Rules for writing of distribution of electrons in various shells for the first 18 elements


The various rules for writing of distribution of electrons in various shells of an atom are as follows :(0 Ttu? maximum number of electrons which can be accommodated in any energy level of the atom of an element is given by 2n2 (where n is the number of that energy level).By using this relation we will find that:
(a) the maximum number of electrons which can be accommodated in 1st energy level (n = 1) or K shell is 2 x(1)2= 2 x 1 = 2
(b) the maximum number of electrons which can be accommodated in 2nd energy level ( n = 2) or L shell is 2 x(2)2 =2x4 = 8.
(c) the maximum number of electrons which can be accommodated in 3rd energy level (n = 3) or M shell is 2 x (3)2 = 2 x 9 = 18
(d) the maximum number of electrons which can be accommodated in 4th energy level (n = 4) or N shell is 2 x(4)2 = 2 x 16 = 32.
(ii) The outermost shell of an atom cannot accommodate more than 8 electrons, even if it has the capacity to accommodate more electrons (If,however, the outermost shell of an atom is the first shell or K shell,then it cannot accommodate more than 2 electrons).
(iii) The electrons in an atom do not occupy a new shell unless all the inner shells are completely filled with electrons.This means that first all the electrons fill K shell,then L shell, then M shell,then N shell,and so on.

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Notes


Structure of the Atom - Notes
1. Drawback of Rutherford’s Model of the Atom
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2. Rutherford’s Experiment - Discovery of Nucleus
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3. For the symbols H, D and T,tabulate three sub-atomic particles found in each of them.
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4. 4.Isotopes of Neon.
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5. Structure of The Atom - Study Points
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6. Radioactive Isotopes
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7. 3.Isotopes of Oxygen.
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8. Characteristics of a Neutron
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9. Nucleus
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10. Arrangement Of Electrons In The Atoms
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11. Characteristics of an Electron
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12. (b) Valency of Magnesium
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13. Limitations of Rutherford's model of the atom
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14. Mass Number
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15. All about Names of the Chemical Elements
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16. (d) Covalency of Nitrogen
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17. How to learn naming Chemical Formulae?
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18. 1. Isotopes of Hydrogen.
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19. Characteristics of a Proton
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20. Comparison between Proton, Neutron and Electron
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21. Electronic Configurations of First 20 Elements
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22. Thomson's Model Of The Atom
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23. Discovery of Neutron
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24. (d) Valency of Chlorine
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25. (e) Valency of Oxygen
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26. Rules for writing of distribution of electrons in various shells for the first 18 elements
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27. Isotopes
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28. 2.Covalency
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29. (a) Covalency of Hydrogen
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30. Covalency of Oxygen
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31. Bohr's Model Of The Atom
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32. Rutherford's Model Of The Atom
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33. 2.Isotopes of Carbon.
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34. Discovery Of Electron
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35. Atomic Number
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36. The Physical Properties of the Isotopes of an Element are Different
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37. (a) Valency of Sodium
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38. Charged Particles in Matter
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39. All the Isotopes of an Element Have Identical Chemical Properties
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40. Discovery of Proton
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41. Valaency Of Elements
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42. Relationship Between Mass Number and Atomic Number
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43. (f) Valency of Nitrogen
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44. Valaence Electrons (Or Valancy Electrons)
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45. Electronic Configurations of Noble Gases (or Inert Gases)
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46. Cause of Chemical Combination
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47. Covalency of Chlorine
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48. Reason for the Fractional Atomic Masses of Elements
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49. Applications of Radioactive Isotopes
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50. Relation Between Valency and Valence Electrons
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