[iScience]

silly question.. but oxygen is an... oxidizer?..   but isn't the stable O2 diatom in reduced mode... which means, if anything, shouldn't it be a reducing agent? because the more stable form of the diatom is not neutral but (O2)^-2? so it would want to give away electrons no?

[magician4]

silly question.. but oxygen is an... oxidizer?..

yes, it is ... in interaction with most of the other elements of the periodic table

but isn't the stable O2 diatom in reduced mode...

with respect to what particle? ( if we'd talk O^2- , which is the most common type of oxygen in compounds, it would be the oxidized form )

because the more stable form of the diatom is not neutral but (O2)^-2

if you went from O₂ to O₂^2- , the molecule would have added two electrons (and not have given them away)

so it would want to give away electrons no?

O₂^2- is a structure in its own right, which can - depending on the situation - go both ways


regards

Ingo

[iScience]

with respect to what particle? ( if we'd talk O2- , which is the most common type of oxygen in compounds, it would be the oxidized form )

i thought O₂^2- was the one found in air

if you went from O2 to O22- , the molecule would have added two electrons (and not have given them away)

i was referring to O₂^2- because i thought that's what was found in air. but, if "oxygen" is an oxidizer, then this would imply that the stuff found in air is O₂ and not O₂^2- right?

[Enthalpy]

Gases comprises neutral molecules. Ions are extremely rare under usual conditions.

O₂ oxidizes other substances, but it dissociates to do so. O₂ has already two electrons on unfavourable orbitals just because O₂^- or O₂^2- attract them; adding more electrons to O₂ would bring nothing.

More generally, atoms are already organized in stable molecules under usual conditions. Very unstable species, like isolated atoms (except noble gas) or species that would accept an electron or let one leave are not the most common case. Instead, reactions transform one set of stable molecules into an even more stable set of molecules.

This means also that some intermediates in the reaction are less stable. Reaction mechanisms search for the less defavourable intermediates and transformations, and need often some energy input (a matchstick) to start.

[magician4]

i thought O₂^2- was the one found in air

no, it isn't
the "common oxygen" found in air is the neutral O₂ molecule

(asides from this, only the very very rare ozone molecule O₃ is another oxygen species that might be airborn )

(...) but, if "oxygen" is an oxidizer, then this would imply that the stuff found in air is O₂ and not O₂^2- right?

though you're right that in fact O₂  is "the stuff in the air" , I don't agree with your line of reasoning: both oxygen and H₂O₂ (i.e. the stem molecule of O₂^2-) can be oxidisers, given the right circumstances

O₂^2- is the dianion of hydrogenperoxide H₂O₂ , an interesting molecule with both oxidising and reducing properties, respectively  - depending on the partners it meets , the situation, i.e. the chemical setup it is subjected to.

the oxidizing properties of O₂^2- could be shown in this equation:
O₂^2- + 2 e-  2 O^2-
this type of process you'll often meet under acid conditions, and should be written (as a half-process) like this:
H₂O₂ + 2 H⁺ + 2 e^-  2 H₂O

... and in fact acidified hydrogenperoxid is a very powerfull oxidizer in its on right then
(in fact you'll meet this combo in lab, where it is used mostly for fast cleanup, it's that powerfull in oxidizing)

O₂ oxidizes other substances, but it dissociates to do so.

just as kind of an academical remark: there also is a bunch of processes where oxygen will attack / oxidize other substances without dissociating (think of the formation of sodium peroxide from burning sodium in pure oxygen)

O₂ has already two electrons on unfavourable orbitals just because O₂^- or O₂^2- attract them; adding more electrons to O₂ would bring nothing.

I am not sure that I understand what you mean for the first part (could you pls. expand on this?) , and with all due respect, I disagree on the second part: there's several processes known where adding one or two electron(s) to the still intact oxygen molecule will "bring a lot" for the overall situation, for example:
O₂ + e^-  O₂^-
( as known from reacting potassium with pure oxygen : K + O₂  KO₂ )
O₂ + 2 e^-  O₂^2-
(as known from reaction of sodium or barium with pure oxygen:   2 Na or Ba + O₂  Na₂O₂ or BaO₂)


regards

Ingo

[opsomath]

The short version is that O2 (the form found in air) can be both oxidized and reduced. However, most of the reactions that it does, it is acting as an oxidizer.

For instance, any time you burn an organic thing in oxygen, you are making H2O and CO2. Oxygen has a -2 oxidation state in both of those compounds, but a zero oxidation state as O2. So, it gets reduced in the reaction...meaning that it oxidizes something else. Make sense?