Question regarding on oxidation numbers of atoms and charge of an ion?

Is it possible to determine the oxidation number of the atoms if you are not given the charge of the molecule? For example PO4^-3. Is it possible to determine the oxidation number for phosphorus and oxygen without knowing the charge of the ion?Question regarding on oxidation numbers of atoms and charge of an ion?
If you know enough about chemistry i suppose you can figure it out though unless you were going to to alot of extra work it is probably easier to just know them or to look them up. Your example of P04 has a structure that looks like this :





......0-


......|


-O-P=O


......|


.....O-





If you know the structure you can count the charges on the loose ends of the molicule to get the charge so I would say that you can but it would require you to know the structure of the Ion.


Pls ignore the periods in the sketch couldn't get formating to stick just using spaces.Question regarding on oxidation numbers of atoms and charge of an ion?
It is not generally possible. Consider the ferrocyanide and ferricyanide ions [Fe(CN)6]4- and [Fe(CN)6]3-, respectively (also called hexacyanoferrate(II) and hexacyanoferrate(III)). They are identical up to charge, but the first contains iron(II) and the second iron(III).


Another example: the permanganate (MnO4-) ion has manganese in its +7 oxidation state; there is also a MnO4 ion with a double negative charge called manganate, with manganese in its +6 oxidation state.


But in simple cases such as PO4 you may be able to apply intuition. Also, if you remember the formula of the parent acid then you'll know the charge of the ion.