What is the periodic trend in the variation of valency while going down a group? Explain your answer with reserence to the group 1, group 2 and group 18.

What is the periodic trend in the variation of valency while going dow

1.	What is the periodic trend in the variation of valency while going down a group? Explain your answer with reserence to the group 1, group 2 and group 18.
Answer» Solution : The velency of an element is determined by the number of valuence elenctrons persent in the outermost shell of an atom of an element. All the elements in a grop have the same numbr of VALENCE elements. Therefore, elements in the same GROUP should have the same valency. For example, the elements of group , the valence electron, the valency of elements of group 1 is ONE. Similarly for group 2, (Be, Mg, Ca ) contain two valence electrons, the valency of elements of group 2 in two. The elements of group 18 (Ne ,Ar ) contain 8 electrons (exception, HELIUM contain 2 electrons). Since the octect is complected their valency is zero.