Question

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

name of the element.

Answer 1

Element $X$ is:

• The element $X$ belongs to third period so it will have three shells, that are $K,L,M$. The number of period is equal to number of shells.
• It has$7$ valence electrons, that means its electronic configuration will be $2,8,7$. The group number $17$ also indicates that its valence electrons will be$7$.
• Its atomic number is therefore $17$. Chlorine is an element which has an atomic number of $17$.
• Therefore, element $X$ is chlorine $\left(Cl\right)$.