* Cobalt is a metal, and metals tend to lose electrons to form positively charged ions (cations).
* Bromine is a nonmetal, and nonmetals tend to gain electrons to form negatively charged ions (anions).
In this case, cobalt will lose electrons to form the Co³⁺ cation, while bromine will gain electrons to form the Br⁻ anion. The electrostatic attraction between these oppositely charged ions creates the ionic bond that holds them together in the compound cobalt(III) bromide (CoBr₃).
