Why do elements in the first group and 17th group elements show the same valency?

Asked by Ganesh | 16th Oct, 2017, 06:50: AM

Expert Answer:

Valency is the combining capacity of the elements.
First group elements are alkali metals which give away one electron while combining (bonding) with other element.
17th group elements are halogens which accept one electron while combining (bonding) with other element.
Oxidation state of alkali metals is +1 and that of halogens is -1.
But, valency does not have any sign as it is just combining capacity of that element, hence valency of both alkali metals and halogens is same i.e. 1.

Answered by Prachi Sawant | 16th Oct, 2017, 09:47: AM