Oxygen Ion Charge

[JavierMelgoza2E]

Looking at Redox rules that some of the elements have and I saw that Oxygen has a -1 charge rather than a -2. How can that be? Is there certain compounds that will cause oxygen to have a -1 charge? Does oxygen impact the charge on other elements as well? Thanks!

[kimberly_oka_2j]

Yes, there are some exceptions to the typical -2 oxidation number of oxygen. One example is in peroxides (H2O2). Because the compound is overall neutral and because the oxidation number of hydrogen +1, the oxidation number of oxygen must be -1. Another example is in F2O. Fluorine is more electronegative and has an oxidation number of -1 so the oxygen in that molecule has to have an oxidation number of +2. I hope this helps! Generally, you need to pay attention to the presence of hydrogen and the electronegativity of a specific element.

[Grace_Bower_2B]

Do you have the rules written out somewhere, because I'm not sure what you're talking about? Oxygen almost always has an oxidation state of -2 (like you would expect from its position in the periodic table and it's electron configuration).
There are certain compounds that cause oxygen to have a -1 charge, peroxides and F₂O.
Atoms in compounds can impact the charge on other atoms in the compound. For example, oxygen has an oxidation state of -1 in hydrogen peroxide because H₂O₂ is a neutral compound. Therefore, the sum of the oxidation states of the atoms is equal to zero. Hydrogen has an oxidative state of +1 so oxygen must have an oxidative state of -1 to make the neutral compound. In the case of F₂O, fluorine is more electronegative than oxygen so it pulls the electrons toward it, making oxygen act positive.

[Laura_funes_1j]

In addition, oxygen can even have a -.5 charge in superoxides.