Greetings ! I have a little question. My teacher was talking about stable ions some days ago, he wanted to explain why do we have certain stable ions in ionic compounds and we don't have other ions. For example, we notice that the stable ion of Na (in its compunds) is Na+1 and not Na+2 or Na+3. The teacher explained this depending on the ionization energy, he says that there is a big difference between the first and second ionization energy of Na (since we are taking the second electron from a completed shell nearer to the necleus), So it is easier (during a reaction) to take off one electron than 2 of them. When he tried to use the same way with Mg, he said there is a big difference between the second and third ionization energy, therefore it is easier to take off 2 electrons than 3. So the stable ion is Mg+2. But .. thinking about this his way, it doesn't make a lot of sense. Since it is even easier (in Mg) to remove only one electron, and make Mg+1, right ? Before he said that, i used to think that the stable ion charge depends on how many electron the atom needs to loose/gain to actually become stable (you know, normally have a last shell with 8 electrons). Any comment/help in making me understand where i went wrong, or where i am missing sth would be appreciated.