Why is diatomic oxygen such a powerful oxidising agent if it is stable?

[Justin Hawk]

I am very confused - any electrons added to dioxygen must inhabit an anti-bonding molecular orbital which leads to destabilisation of the molecule. So why is dioxygen such a powerful oxidising agent?

I need to understand this to try and figure out why nitrogen monoxide is readily oxidised by dioxygen to nitrogen dioxide. At the moment my reasoning is that the more electronegative oxygen molecule attracts the unpaired electron from the NO molecule, forming NO+ and causing the now ionised dioxygen to separate to O- and an oxygen radical. The NO+ and O- then react to form NO2. This can't possibly be the mechanism through which the bonding occurs, but I can't find any sources online. Can someone please explain this to me?

 

[jbsteele]

The powerful oxidizing ability of dioxygen is due to its ability to form stable, highly reactive oxygen radicals. These oxygen radicals are formed when two oxygen atoms share two unpaired electrons in a process known as homolytic cleavage. Since both oxygen atoms have an unpaired electron, they become highly reactive and can accept electrons from other molecules, thus oxidizing them. In the case of nitrogen monoxide, the oxygen radical can accept an electron from the NO molecule, forming a NO+ ion and a separate O- ion. The NO+ and O- ions then react to form NO2, thus completing the oxidation reaction. This type of reaction is why dioxygen is such a powerful oxidizing agent—it has the ability to quickly and efficiently form highly reactive oxygen radicals that can accept electrons from other molecules.