In chemistry it is common sense that we have O$^{2-}$. But from a physical point of view, does O$^{2-}$ really exist as a negative ion? I mean, as an isolated ion.
It is not apparent that a neutral atom like oxygen can bound two extra electrons.
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1$\begingroup$ In general, if you can get the second extra electron on it, the species will auto-ionize back to -1 very quickly. I would love to be able to get 2- ions to inject into a tandem accelerator, but alas none of them make it our of the ion source, much less to the terminal. $\endgroup$ – Jon Custer Apr 8 '15 at 14:04
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1$\begingroup$ Would Chemistry be a better home for this question? $\endgroup$ – Qmechanic♦ Apr 8 '15 at 16:31
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$\begingroup$ It is a physical problem --- whether O$^{2-}$ is stable or not. $\endgroup$ – Jiang-min Zhang Apr 8 '15 at 17:13
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1$\begingroup$ As I said it is a "Physical Chemistry" problem. you can not say which major it is for(although officially and academically it is a chemistry major) $\endgroup$ – Mobin Apr 8 '15 at 18:31
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No! In chemistry this is called "Radical Ions". some of the radicals can exist, but it is very hard to find them in the nature because they interact very fast.
So the question is how can you understand that a radical exist or not? well you have to know "Physical Chemistry".
the Radical that You mentioned can not exist, because of high density of charge on the atom. so the oxygen will quickly bond with other atoms or shoot one electron out.
You can read about radical in here
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The oxygen 2- ion will interact with other atoms to turn into an ionic bond. However sometimes these ions could exist(for example in water-magnesium oxide for example turns into magnesium 2+ and oxygen 2-) however it is only possible in liquids. Even here it is just not considered the oxygen is free because they will just consider the compound in an aqeous solution.
