Answer;
- Bromine
This is because bromine only needs one electron to have a full octet.
Step-by-step explanation;
-Atoms can attract additional electrons if there is room for them in the valence energy level.
-The effective nuclear charge is largest for the elements on the right side of the periodic table (it increases as you go across the period due to addition of an extra proton in the nucleus), those atoms provide the greatest attraction for electrons and have the greatest tendency to gain electrons.
-The tendency of atoms to gain electrons increases as we go from left to right across the periodic table.