Question

what is the periodic trend in the variation of valency while going down a group? explain your answer with reference to group 1, group 2 and group 18​

Answer 1

Valence numbers do not vary as you go down a group, since the periodic table is arranged by atomic number and chemical properties. All members of a group have the same number of valence electrons. Group I has 1, Group II has 2, Group III - XII has 2, since only s or p electrons are counted as valence electrons, Group XIII has 3, Group XIV has 4, Group XV has 5, Group XVI has 6, Group XVII has 7 and Group XVIII (noble gases) have 8.

Answer 2

Answer:

Explanation:

(i) All the elements in a group have the same number

of electrons in the outermost shell. Therefore,

down the group, valency remains the same.

(ii) Valency of group 1 elements is 1 and that of group

2 elements is 2.

(iii) The valency of group 18 elements is zero because

they are noble gases with completed outermost

shell.