1. The problem statement, all variables and given/known data When does an atom become a cation and an anion? 2. Relevant equations 3. The attempt at a solution Cations have a positive charge because they lose electrons, and anions have a negative charge because they gain ions. The atom would always want to do what requires the least energy, like if it has 1 electron in its valence shell, it will give it away, becoming a cation, while if it has 6 electrons in it valence shell, it will gain 2, becoming an anion. So basically, if an atom has over 4 electrons in its outer shell, it will become an anion, and if it has under 4, it will become a cation. Now my confusion is, what if it has 4 electrons in it's valence shell.. Like Silicon, does it lose them or gain 4? I am only referring to when there are 8 electrons in the valence shell.