Oxygen is found in 3 forms: nascent (O), molecular (O2, the most common) and ozone (O3). Nascent oxygen, due to its electronic configuration (i.e how many electrons it has and how they're spread out across its electronic shells) is unstable, and tends to quickly form bonds with another O, forming O2. This is also the case e.g. for hydrogen, which is usually found as H2.
You can find O in this form in some environments, in the upper atmosphere there is enough UV radiation to break up O2 into O.
Not just with itself, also with other elements. Say, you won't find pure iron in the wild either, because normally it reacts with oxygen so well.
But yea oxygen needs to pair with something because its outer electron shell is incomplete. So pairing with another oxygen atom is likely, but also with whatever else is available - nitrogen, iron, whatever.
Most elements are found in molecules really, with the exception of noble gasses like Helium. And some are less reactive than others.
I don't know if anyone is interested but there would be more versions too. Solid oxygen (red oxygen) at high pressure used to be thought of as O4, tetraoxygen aka oxozone. But if you look at it with x-ray crystallography it's O8, octaoxygen. Cool huh
This question doesn't even make sense. If atomic oxygen somehow magically appeared in your respiratory tract, it would immediately react with itself and probably burn you to death.
Yes. Nascent oxygen (O) is very reactive, somewhat like peroxide and ozone, so it could be used to burn off organic matter.
Now, if you don't want it to react (too fast) with itself and produce molecular oxygen you may dilute it at low concentration into some inert gas (nitrogen or helium for example).
Taking 2 or 3 breath of this gas mixture once in a while would eventually get @WtfEvenIsExistence1
with Acute inhalation injury