1. The problem statement, all variables and given/known data Ok, I recently started studying again after a 1.5 year break to pursue other things. I am trying to plow through this chemistry course, and I remember this forum where I basically got through my entire physics course because of the help of this forum which I greatly appreciate. Ok, this is very simple but I have a hard time understanding this. Why does sulphate have 4 oxygens and -2 charge. I have a series of questions in my course, and among it, it said to write the formula for Aluminium chloride for example, which I understand is AlCl3 since Al has +3 charge and Cl has -1 so there has to be 3 of Cl to even things out, right? But this problem with writing sodium sulphate has me confused. I see that Sulfur and Oxygen is combined to make sulphur, but why on earth does it have to be 4 oxygens and 1 Sulfur? In my mind both needs 2e- to be happy, so why can't they just share it? If one atom of Sulfur shares with 1 atom of Oxygen, wouldn't they be happy? They could share one electron each and be content? Do I just have to learn in my head that sulphate has the formula So42-? Likewise nitrate has NO3? I am sorry, I am just massively confused by this. Regards Sonny PS: If this is not worthy to be a thread I apologize, and if it is in the wrong place, please remove.