Bromine has 7 electrons in its outer shell, so normally it's an anion—it borrows an extra electron to keep a full set of 8. However, in the presence of fluorine or chlorine, bromine can donate electrons and become a cation. +3 Bromine has a two pairs of electrons in its outer shell, and +5 Bromine has a single pair.BrCl3, BrCl5, BrF3 and BrF5 are all VERY VERY VERY energetic and unstable, though—it takes a huge amount of energy to persuade a bromine atom to donate electrons rather than receive them, so these compounds tend to decompose quite readily and violently.