## Chemistry: A Molecular Approach (3rd Edition)

Bromine is a main group element. Therefore, its valance electrons are those in the outermost energy principal level. The noble gas configuration for Bromine is $[Ar]4s^{2}3d^{10}4p^{5}$. Therefore, Bromine has seven valance electrons. Since, Bromine is a non-metal, it is expected to gain electrons in chemical reactions.