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A formula written above a reaction arrow, naming a catalyst.
Also known as: Above the arrow notation, Catalyst label
A substance written above the arrow rather than beside the reactants is a catalyst: it takes part and is not consumed. Its position states that, which is a piece of chemistry expressed purely by layout.
Names a catalyst by writing it above the reaction arrow rather than among the reactants.
Contexts: Laboratory
States by its position that the substance is not consumed: anything written among the reactants is used up, and anything above the arrow is not.
Contexts: Laboratory
Shares the space above and below the arrow with reaction conditions such as temperature, pressure and solvent.
Contexts: Laboratory
A chemical formula or abbreviation set in small type directly above the shaft of a reaction arrow, with conditions sometimes written below it.
The notation is a use of the arrow's surrounding space.