How Can You Predict If an Element Will Form a Cation or an Anion?

It is possible to predict whether an element will form a cation or anion by determining how many protons an element has. If an element has more protons than electrons, it is a cation. Elements with more electrons than protons form an anion. When two elements are mixed, the amount of ionization energy determines whether the new substance will turn into a cation or anion.