Relation Between Valency and Valence Electrons
The valency of an element depends on the number of valence electrons (outermost electrons) in its atom because only the valence electrons take part in chemical bonding.The valency of an element is either equal to the number of valence electrons in its atom or equal to the number of electrons required to complete eight electrons in the valence shell.For example, sodium has 1 valence electron and the valency of sodium is also 1. So,in the case of sodium, the valency is equal to the number of valence electrons in its atom. In general,the valency of a metal element is equal to the number of valence electrons in its atom.That is,
Valency of a metal = No. of valence electrons in its atom
Let us discuss the case of non-metals now. Chlorine has 7 valence electrons but its valency is not 7. Chlorine atom requires 1 electron to complete the 8 electron structure, so the valency of chlorine is 1. Thus,in the case of chlorine, valency is equal to the number of electrons required to complete 8 electrons in the valence shell. In general,the valency of a non-metal element is usually equal to eight minus the number of valence electrons in its atom.That is,
Valency of a non-metal = 8 - No. of valence electrons in its atom
There is one exception to this rule and that is the valency of hydrogen. The valency of hydrogen is equal to the number of valence electrons, which is 1 (though hydrogen is a non-metal element).
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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5. Structure of The Atom - Study Points
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9. Arrangement Of Electrons In The Atoms
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13. Limitations of Rutherford's model of the atom
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15. All about Names of the Chemical Elements
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17. How to learn naming Chemical Formulae?
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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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26. Rules for writing of distribution of electrons in various shells for the first 18 elements
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36. The Physical Properties of the Isotopes of an Element are Different
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39. All the Isotopes of an Element Have Identical Chemical Properties
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42. Relationship Between Mass Number and Atomic Number
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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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48. Reason for the Fractional Atomic Masses of Elements
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49. Applications of Radioactive Isotopes
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