Here's why:

* Electronegativity: Bromine is a nonmetal with a high electronegativity. This means it has a strong tendency to gain electrons.

* Electron Configuration: Bromine has 7 valence electrons. It needs one more electron to achieve a stable octet configuration like the noble gas krypton.

* Ionic Bonding: Bromine readily accepts one electron to form a bromide ion (Br-), which has a -1 charge.

Therefore, bromine typically forms an anion, not a cation.