Two half-headed arrows pointing opposite ways, marking a reversible reaction.
Also known as: Reversible arrow, Two half arrows, Harpoon arrows
Two half-arrows pointing opposite ways mark a reversible reaction at equilibrium. Drawing one longer than the other says which side is favoured — a quantitative statement made by line length.
Marks a reaction proceeding in both directions simultaneously, with reactants and products both present at equilibrium.
Contexts: Laboratory
Is drawn with half-arrowheads — barbs on one side only — which distinguishes it from a plain double-headed arrow meaning something else entirely.
Contexts: Laboratory
Says which side is favoured by drawing one arrow longer than the other, a quantitative statement made purely by line length.
Contexts: Laboratory
Two parallel horizontal arrows one above the other, the upper pointing right and the lower left, each with a barb on one side of its head only.
Both are double arrows between structures and they mean opposite things.
The chemical arrow family.