Question

Name two elements belonging to group one. Also write their valencies.​

Answer 1

The valency of an elements is determined by the number of valence electrons present in the outer shell of an atom. Since all the elements of a group have the same number of valence electrons. Therefore, they have same valency.

For example, alkali metals have one valence electron. Hence, their valence is 1. Similarly, alkaline earth metals have two valence electrons. Hence, their valence is 2.

Answer 2

Answer:

(1) The valency of an element is determined by the number of valence electron in the outermost shell of an atom of an element. (2) All the elements in a group have the same number of valence electrons. Therefore, elements in the same group should have the same valency.