Question

Why the valency of argon is zero....its 3rd shell need 18 electron
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Answer 1

Because for being valanced there is need to complete duplet or octate.

According to Bohr bury rule we fill electrons as 2,8,8,2 in k,l,m,n respectively. Since in third shell there are 8 electrons in its outermost shell and is stable. Hence, its valency is zero.

Valency means the combining capacity of an element.

Hope this helps you..