Why does SO4 have a 2- charge?
The Sulphur expands its octet in order to form a double bond with three of the oxygen molecules. This gives the sulphur 12 electrons in its outer shell, and the three oxygen molecules 8 electrons in their outer shell. The fourth Oxygen molecules then forms a double dative covalent bond with the Sulphur, sharing 4 of its electrons with the sulphur to form a double bond. The sulphur now has 16 electrons in its outer shell This fourth oxygen therefore only has 6 electrons, which is not stable, so when the SO4 bonds the fourth oxygen recieves 2 electrons from the substance the SO4 is bonding with (for example magnesium). This gives the 2- charge, as this fourth oxygen ion has 2 more electrons than it has protons. Sorry I can’t include a diagram there don’t appear to be any on the internet. Additional – Cubola Zruka, your answer doesn’t work. Each of the oxygen atoms would end up with 7 electrons in the outer shell, which isn’t stable, they need to have 8.
