Question

How to remember first 18 elements and valency

Answer 1

learn there atomic number and do atomic cofiguration and the valence electrons is the valency of that element. If the valence electron is 1,2,3,4 than the valency of the element is 1,2,3 or 4 but if valence electron is 5,6,7,8 then subtract them by 8 and u will get the valency of that element.