# Why don't such ions form if half-filled or full-filled configurations are considered stable?

We all know atoms want to stabilize by having an octet or duplet configuration. But if you see nitrogen which has an electron configuration of $\ce{2p^3}$. It has half filled p orbital, so it is technically stable, isn't it? Then why don't elements like oxygen form a monovalent oxygen ion?

By similar logic, sodium has $\ce{3s^1}$ configuration which should also be stable because it has a half filed orbital. But sodium is reactive as we know.

Can you please point out the flaw in my argument?

• Nitrogen which has am electron configuration of 2p3. It has half filled p orbital, so it is technically stable right? No, a N atom is not stable in that two such atoms will form a molecule $\ce{N2}$. – MaxW Jul 6 '18 at 18:23
• Stability is relative. A half-filled orbital configuration is more stable than usual, but not as stable as an octet, etc. – a-cyclohexane-molecule Jul 6 '18 at 18:28

You may have come across the fact - that half-filled configurations are "stable" - while studying ionization enthalpy/electron gain enthalpy, or the electronic configuration of $\ce{3d}$ elements. Pay careful attention: the half-filled configuration is "stable", but only with respect to the neighbouring configurations. That is to say, the $\ce{2p^3}$ configuration is much stable than $\ce{2p^4}$ or $\ce{2p^2}$. Yet, $\ce{2p^3}$ is still very less stable than $\ce{2p^6}$. This is why, in nature, nitrogen prefers to exist in diatomic molecules, so as to complete its octet.
Now for the fully-filled $\ce{3s^2}$ configuration (sodium anion, aka "sodide"): again, note that the sodium cation is way more stable than the sodium anion, as the former has a fully filled octet, while the latter doesn't. (Sodide has indeed been formed, but by using special techniques only. See Wikipedia).