Question

(i) How do you calculate the possible valency of an element from the electronic configuration of its atoms? (ii) Calculate the valency of element X whose atomic number is 9.

Answer 1

If The Element X has atomic No.9 so its Electronic Configuration Is 2,7 So to get Stable Electronic Configuration [Octet Rule 2,8] It has to gain One Electron So it has to receive One Electron So its Valency is -1

If An Element Is Donating Electron Den its Valency would be in Positive
But
If An Element Is Receiving Electron Den its Valency would be in Negative

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Answer 2

we can calculate the valency of an element by electronic configuration by looking at the outermost shell that how many elctron that element has to gain or loose to complete octat law.

if atomic number is 9 then elctronic configuration is 2,7.

therefore the element needs 1 more electron more to complete octet law

therefore, its valency is 1