Argon is a noble gas and is generally considered to be non-reactive. It has a full valence shell, meaning that its outer energy level is completely filled with electrons. This makes it very stable and unlikely to react with other elements.

In the case of oxygen, argon does not react with it under normal conditions. This is because oxygen is also a relatively non-reactive element. It has a full outer energy level except for two unpaired electrons. These unpaired electrons can form covalent bonds with other elements, but they are not very reactive.

At extremely high temperatures, it is possible for argon and oxygen to react to form argon monoxide (ArO). However, this reaction is very slow and only occurs at temperatures above 1,500 degrees Celsius.

In summary, argon is a non-reactive element and does not react with oxygen under normal conditions.