Please forgive me if this is a stupid question; I know embarrassingly little about chemistry. I'm just curious as to whether water breaks down or not: if one leaves out, e.g., a piece of bread , within a few days, the bread will become moldy, i.e., it will start breaking down (same thing will happen even if bread is refrigerated, only slower). Yet, it seems, when one leaves out a glass of water, that this water does not break down, at least not in a way similar to, e.g., that of the bread. I guess this has to see with the strength of the bonds between the molecules , maybe with entropy in a more general sense (and I know of this in only very general terms). I guess water is chemically very simple, having two hydrogens and one oxygen, still, I know next to nothing about the strength of the link/bond between the hydrogens and the water. Is this the explanation?