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CHEMICAL TERMS

Do not capitalize or hyphenate compounds as nouns.

Hyphenate as adjectives only if necessary for clarity:
            carbon dioxide
            carbon dioxide test
            carbon monoxide fumes
            iron-oxide red

Hyphenate elements with mass numbers:
            strontium-90
            strontium-90 fallout
            Sr-90
            carbon-14
            C-14
            carbon-14 dating

Use an inferior number after an element to indicate the number of atoms in a molecule:
            CO2        H2O

In technical papers, use a superior number before an element to indicate the mass number:
            18O