The most straightforward way to approach this would be to consider several equilibria constituting (1) dissociation of the oxide and (2) reactions between the oxide ion, hydroxide ion, and water. At equilibrium free oxide concentrations would be very low, perhaps not even measurable.

A more advanced picture would consider heterogeneous equilibria at the metal oxide surface. In aqueous suspension, most oxides exhibit various degrees of protonation at the surface. Dissolution of the oxide is a complex process involving different crystalline faces, defect cites, and so forth.

This is only dissociation  of sodiumchloride, no chemical reaction. Here we don't use the word spectator ions.

For exqmple

AgNO3 + NaCl => AgCl(s) + NaNO3.

Sodium and nitrate are spectator, because they stay in solution. Only Silver and chloride form silverchloride as precipitate.

NaCl(aq) + AgNO3(aq) ⟶ AgCl(s) + NaNO3(aq)

NaCl is soluble ionic as is AgNO3 so should be broken up as


Na+(aq) + Cl-(aq) + Ag+(aq) NO3-(aq) ⟶ AgCl(s) + Na+(aq) + NO3-(aq)

So fine I can see Na+(aq) and NO3-(aq) are solvated ions on both sides..

no phase change.

I think that's the normal definition of spectator ions that i'm used to.

Applied where the spectator ions are compound that ionise, so "in" soluble ionic compounds so i.e. as solvated ions, (or perhaps floating around without a counter-ion, still a solvated ion).   Or an ionising polar covalent compound like HCl.

You don't count the silver ion and chloride ion in the precipitate , as spectator ions. because they're not solvated ions.

So I agree with that

The solid Na2O will not dissolve as Na2O(aq) it reacts directly to form Na+( aq) and OH- (aq) ions.

I agree, we don't have Na2O(aq)   or 2Na+(aq) + O2-(aq).  It's not like HCl(which is covalent and ionises) or NaCl(a soluble ionic compound, so ionises).  It doesn't "ionise"/dissociate. And is not like NH3(aq)(covalent, but doesn't ionise).   It's Na2O(s), a crystal (or amorphous solid).
 
So in agreement so far.

Na+ is spectator because it is not changed.

The main reaction is
O2- + H+ OH- ( H2O)  => 2 OH-

You get from sodiumoxide sodiumhydroxide.

I think perhaps most would disagree with the idea that Na+ is a spectator.

I agree that Na+ hasn't changed oxidation state.  And, that a reaction occurred. But it has changed physical state, which means it took part in the reaction.

Also , if you see here

How to Write the Net Ionic Equation for Na2O + H2O = NaOH
Wayne Breslyn
https://www.youtube.com/watch?v=MLNbUC9fhr8

He speaks of the "complete ionic equation"  (which includes spectator ions)

And he speaks of the "net ionic equation" (which excludes spectator ions)

And he says there are no spectator ions, so for that equation,  Na2O(s) + H2O(l) --> 2Na+(aq) OH-(aq)


I agree that Na2O does split/dissociate/ionise, as part of the reaction. But I think to be a spectator ion, it has to split before the reaction. i.e. it has to be in split form as a reactant. (not just in the products).

Thanks

Yes, but I meant sodium  stays as a Na+, doesnt matter as solid or in solution. So it's a spectator. The oxide anion is in water not stable and changes to hydroxide by adding one hydrogen from the water.

Thanks.. Isn't one of the ideas with spectator ions, that you can cancel them out because they're solvated ions on both sides?

Or is your definition of spectator ion that it doesn't have to be solvated ions on both sides. Just on one side, particularly the right side?

So NaCl(s) + H2O(l) --> Na+(aq) + Cl-(aq)

would you say that Na+ and Cl- are both spectator ions on the right there?

Na+ is spectator because it is not changed.

The main reaction is
O2- + H+ OH- ( H2O)  => 2 OH-

You get from sodiumoxide sodiumhydroxide.

The solid Na2O will not dissolve as Na2O(aq) it reacts directly to form Na+( aq) and OH- (aq) ions.

The Na+ did go from solid phase (before reaction)  as it's part of Na2O(s).

To aqueous phase (after reaction), where it's Na+(aq). 

Isn't that a change?