Question

State the valency of the elements of period 3 and write the formula of their oxides.

Answer 1

The elements of third period are Na,Mg, Al,Si,P,S,Cl and Ar.
Their valencies are 1,2,3,4,3,2,1,0 respectively.
The formula of their oxides are Na2O, MgO, Al2O3,SiO2, P2O5,SO3, Cl2O7

Answer 2

The valency increases from 1-7 as we move down and than 0
oxides: Na2O, MgO, Al2O3, SiO2, P2O5, SO3, Cl2O7