First it takes an oxygen atom away from an ozone molecule, then the sunlight tears away that atom, leaving the chlorine atom free to repeat the process.

But the tool they were using couldn't detect the difference between water and hydroxyl, a molecule that consists of one hydrogen atom and one oxygen atom.

Consequently, mesomerism occurs, dislocating the negative charge between the alpha-carbon and the oxygen atom.

For example, bases donating a lone pair from an oxygen atom are harder than bases donating through a nitrogen atom.

A carbonyl group can be reduced to the alcohol or the oxygen atom can be removed altogether, a process called deoxygenation.