Question

Explain why elements in groups 1 and 7 have the same valency ?

Answer 1

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.

(3)Valency is the combining power of an element. Elements in the same group of the periodic table have the same valency.

(4) The valency of an element is related to how many electrons are in the outer shell. The noble gases have the valency 0 as they do not usually combine with other elements.

Explanation:

please mark me as brainliest