Question

An element$X$ lies in the third period and group $17$. Find out,

valency of the element $X.$

Answer 1

The valency of element $X$:

1. The valency corresponds to the number of electrons that an element requires to complete its octet.
2. An element can complete its octet by gaining or losing electrons.
3. The number of valence electrons in element $X$ are$7$, so it requires only one electron to complete its octet.
4. As it will gain one electron its valency will be $-1.$