actually, the main idea was like this: you have an ability to control ONE element. Yes, you can control chemical compounds that have same element such as O2. However, you can't control chemical compounds that have 2 different elements such as NaCl (either you control Na or Cl, just one). Plus, you can co-op with the other element controller (e.g. X is a sodium controller, Y is a chlorine controller, then, together, X and Y can make NaCl). Also, let's say we can break any kind of chemical bonds (since that'll need energy, maybe you can use your own stamina).
N.B.: this allows you to have mountains of gold...