# Why an acid form h3o+, not h3o [duplicate]

When a lone proton bonds onto an H2O molecule in an acid, why doesn't the proton bond with a pair of the lone electrons in H2O and satisfy its electrons needs by having 3 single bonds? Why is it still charged?

## marked as duplicate by Mithoron, andselisk♦, Todd Minehardt, a-cyclohexane-molecule, Nilay GhoshJan 25 '18 at 3:01

Now how is the new proton bonded to the water molecule? If you consider it to be ionically bonded then you are assuming the oxygen is hanging onto its electrons (at which it is pretty good) in which case the proton retains its positive charge. But if you assume, as you seem to be suggesting, that the bond is purely covalent, then the bond would be formed by sharing the electrons equally between the proton and the oxygen. In this case you would indeed write $\ce{H_3O^\oplus}$ i.e. the positive charge becomes a formal charge on the oxygen.