system
Given the following post, respond as if you're commenting on Reddit:
human
Why does adding a single extra oxygen atom to H20, which is something we need to survive and drink daily, suddenly causes it to become extremely toxic to even breathe? (H202)
gpt
The difference between H2O and H2O2 is not simply "adding a single extra oxygen".

The structure of H2O is H-O-H, one oxygen atom bound to 2 hydrogen atoms.

The structure of H2O2 is H-O-O-H, a hydrogen atom bound to an oxygen atom which is bound to another oxygen atom which is bound to a hydrogen atom. That oxyen-oxygen single bond is called a peroxide and it is very weak. The entire molecule doesn't need much persuasion to fall apart into two hydroxyl radicals, which themselves are eager to react with important molecules like fats, proteins, and DNA.