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Chemistry
Key terms
Compound ion

GCSE Chemistry · key term

Compound ion

Definition

An ion made from two or more atoms joined together that acts as one charged unit, such as $\mathrm{NO_3^-}$ .

Used by OCR

How each exam board covers it

OCR GCSE Chemistry B · J258

Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)

If more than one compound ion is needed, put its entire formula in brackets before adding the subscript.
Revise: Deducing formulae from ions

OCR Chemistry B past papers

Exam tips

1
Use brackets only when more than one of a compound ion is needed: $\mathrm{Mg(NO_3)_2}$ , but .

Related key terms

Formula unit
Ion
Ionic compound
Subscript
Superscript charge

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Compound ion — OCR GCSE Chemistry B Definition | GradeGen

2

\mathrm{NaNO_3}