A water molecule has 2 hydrogen atoms and 1 oxygen atom. If you were to add an additional oxygen atom to the molecule, would it still be water? If not, what would it be?

No, it would not still be water. it would be hydrogen peroxide

Explanation:

water is . Adding another oxygen would make it , which is hydrogen peroxide

It would be Hydrogen peroxide

Explanation:

Atoms actually prefer being configured as water (H2O). Adding on the extra oxygen takes a lot of energy (and other chemicals). That's why we see lots of water and not much hydrogen peroxide around in nature. The reason hydrogen peroxide (H2O2) is dangerous is because it actually wants to drop off that extra oxygen and become water. Anything that does this is called an oxidising agent. An oxygen atom on it's own is pretty unstable and really wants to snatch up electrons from somewhere. First it'll probably gobble up some free floating hydrogen and make some more water with it. In our bodies we don't have much free floating hydrogen, so it runs out pretty quick. The oxygen atom army then has to start breaking up bigger molecules to steal the hydrogens and sometimes even the nitrogens. This breaks up the molecules that form the structures of your body and leaves you with a jumble of random configurations of atoms where the oxygen atoms passed through. Now, before you ask, normally oxygen doesn't do it to you because it exists in the air as O2, bonded to itself. The isolated oxygen atoms only exist for a brief time after they've split up from the hydrogen peroxide.