O2: meaning, definitions and examples

oxygen provider

O2 is a chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group on the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium.

oxygen.

Which Synonym Should You Choose?

Word	Description / Examples
O2	Used in scientific, medical, or technical contexts to refer to the molecular form of oxygen, especially in formulas and technical documents. The O2 concentration in the patient's blood is critically low. O2 is a diatomic molecule consisting of two oxygen atoms.
oxygen	Used in everyday contexts and in fields like biology or chemistry to refer to the element that is essential for respiration and combustion. Trees produce oxygen through photosynthesis. The diver used a tank full of oxygen to stay underwater.

Examples of usage

• Patients with respiratory problems may require O2 therapy.

• Deep sea divers use O2 tanks to breathe underwater.

• O2 is essential for combustion to occur.

• The atmosphere contains approximately 21% O2.

• Plants produce O2 during photosynthesis.