Knowing how many valence electrons "belong to" a transition metal complex allows us to make predictions about the mechanisms of reactions and the possible modes of reactivity. There are two distinct methods that are used to count electrons, the neutral or covalent method and the effective atomic number or ionic method. While this may seem confusing, these are simply two different accounting systems that give us the same final answer. Although having two systems may seem confusing, it at least provides us a convenient way to double check our answer.