I have a basic confusion regarding polyatomic ions:

Is it meaningful to say "which atom" in a polyatomic ion is charged?

Consider for instance hydroxide OH$^-$:

The oxygen has greater electronegativity than the hydrogen, so it is "more negative" than the hydorgen.

However, I am not sure: Is it wrong to say that the hydroxide is composed of a neutral hydrogen together with a negatively charged oxygen?

I guess this won't be an accurate statement/description, right?

In particular, If I understand correctly, then the formulas OH$^-$ and HO$^-$ describe exactly the same diatomic anion, so in particular on cannot deduce from the formula which is the more negatively charged atom between $H$ and $O$. (For a moment I wasn't sure whether the presence of the minus sign above the $H$ in OH$^-$ means that it's the $H$ that is more negative).

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    $\begingroup$ Your understanding is correct. $\ce{OH-}$ and $\ce{HO-}$ are exactly the same thing. The position of minus does not mean anything. $\endgroup$ May 21, 2022 at 9:35
  • $\begingroup$ See: chemistry.stackexchange.com/questions/53568/… $\endgroup$ May 21, 2022 at 10:38
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    $\begingroup$ All atoms in such a ion are charged, effectively not in integer multiples of the elementary charge. Some are more charged than others. The charge is not limited to a single atom. The sum of atomic charges is equal to the ion charge. $\endgroup$
    – Poutnik
    May 21, 2022 at 12:15
  • $\begingroup$ And charges are not strictly localized, as you state, so think of an electron spending some time in the company of one atom, and sometimes with another. To confuse things more, there may be resonant electron layouts... $\endgroup$ May 22, 2022 at 2:14


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