Question

An element X belongs to group 17 and 3rd period of periodic table write electronic configuration of the element what is its valency it its its nature whether it is a metal or nonmetal give the formula of the compound formed when it combines with an element by having a valency 3

Answer 1

The element X is chlorine
atomic number of chlorine is $17$
electronic configuration is $2,8,7$
valency = $1$
non metal as it will gain an electron to full fill it's eight electron inert gas structure.