What is the valency of Aluminium whose atomic number is 13 ? Give reason.
let me make you understand
see the atomic no. of aluminium is 13
so electronic distribution in K,L,M,N shell is 2 , 8 , 3 respectively
so in the outermost shell the no of electron is 3
it would take less energy to loose 3 electron than to gain 5 more electron to complete its octet
so the outermost shell has 3 electron and it looses 3 electron therefore the valency is 3
it is to be noted that if the outer most electron has 1-4 electron it looses them but if the electron is 6-8 it gains electrons
if the electron in the outermost shell is 5 then the valency is alwayz 0
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