How will we know the charge of valencies of atoms having four electrons in the outermost shell?

Dear student,

In the case of elements (say, X)  having 4 electrons in valence shell, they need to gain or lose four electrons to attain noble gas configuration. If it were to gain or lose electrons –
(i) It could gain four electrons forming X4– anion. But it would be difficult for the nucleus with lesser protons to hold on to so many electrons, that is, four extra electrons.
(ii) It could lose four electrons forming X4+ cation. But it would require a large amount of energy to remove four electrons leaving behind a cation with more protons in its nucleus holding on to lesser electrons.

Such elements overcomes this problem by sharing its valence electrons with other atoms of  identical species or with atoms of other elements. Many elements, like Carbon, Silicon,etc. form molecules by sharing electrons in this manner. The shared electrons ‘belong’ to the outer shells of both the atoms and lead to both atoms attaining the noble gas configuration. This is called covalent bonding.

Hope it helps you!!

Regards

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