Group VI and VII elements like oxygen are also reactive as they seek electron pairs to complete their outer shell octet. Calculate the valencyof an element using the total number of electrons. The valency of anatom is equal to the number of electrons in the outer shell if that number is four or less.
Valency - it is the combining capacity if an atom. Fem 1 - 4 the valency remains the same. N frm 5...subtract it with 8. Like for example.. atomic no: of carbon is 6 So it's electronic configuration will be 2 ,4. Therefore it's valency = 4 Anthr example - the atomic numbr of nitrogen is 7. Therefore it's E.C will be - 2,5 Valency = 8-5=3 Hope it helped