Answer:
Fluorine
Step-by-step explanation:
Halogens is the group right before Noble Gases, or Group 17. They consist of (from Period 1 to 7):
2 - Fluorine
3 - Chlorine
4 - Bromine
5 - Iodine
6 - Astatine
7 - Tennessine
We can see from the Periodic Table of Elements that Fluorine will be our answer.