What is the chemical symbol for oxygen?

The chemical symbol for oxygen is represented as O2 because this notation indicates that two oxygen atoms are bonded together to form a diatomic molecule, which is the most common and stable form of oxygen found in nature. Oxygen in its molecular form (O2) is essential for respiration in most living organisms, as it is utilized in cellular processes to produce energy.

On the other hand, O3 denotes ozone, which is a different allotrope of oxygen that consists of three oxygen atoms. O is the symbol for a single oxygen atom, representing the atom itself rather than its most usable form. OH refers to the hydroxyl group, which is part of many compounds, but it does not represent elemental or molecular oxygen directly. Thus, O2 is the correct representation for the diatomic molecule of oxygen that is fundamental to life on Earth.