Plural of dioxide; chemical compounds each containing exactly two oxygen atoms bonded to another element, like CO₂ or NO₂.
From 'dioxide' (di- + oxide) + English plural '-s.' The term standardized in the 19th and 20th centuries as chemistry developed systematic naming conventions.
Carbon dioxide, nitrogen dioxide, sulfur dioxide—these dioxides are everywhere in the atmosphere and chemistry labs, and their names all follow the same pattern showing they each have exactly two oxygen atoms!
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