Question

How can a valency be determined if the electronic configuration is given ? Of a given element

Answer 1

In case of elements having valence electron above 4.
valence electron(electron present in outermost shell) - 8.

In case of elements having valence electron less than 4.
Valence electron become the valency

Answer 2

the last shell is considered as valance shell and by the electronic configuration we can easily detect it. Eg - Sodium, 2.8.1 . it's valency will be 1 bcz it is the outermost electron
But if it has its outermost electron 5,6, or 7 then we have to subtract it from 8 like - nitrogen, 2.5 which has its outermost electron 5 so to find its valency we have to subtract it from 8 . so it's valency will be 8-5= 3
By this way we can you can find valency of every element.
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