Different substances of the same elementary system are called allotropes or allotropic modifications. In the case of oxygen, there are two allotropic modifications: "normal" dioxygen (O2) and trioxygen (O3) or ozone.
Generalic, Eni. "Allotropic modification." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. 14 Apr. 2025. <https://glossary.periodni.com>.
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Periodic Table