Answer :
Given configuration
[tex]\\ \bull\leadsto 1s^22s^22p^63s^23p^5[/tex]
- Its a halogen family element hence valency is 1
- The element present in 3rd period Group 17
- The element is Bromine(Br)
Given configuration
[tex]\\ \bull\leadsto 1s^22s^22p^63s^23p^5[/tex]