Draw
the reaction, and then click the Map
Atoms 
icon.
Click the atom in the reactant, and
then click the atom in the product.
Map numbers appear on the atom pair.
Specify corresponding pairs of atoms present in the reactant and product.
Draw
the reaction, and then click the Map
Atoms
icon.
Click the atom in the reactant, and
then click the atom in the product.
Map numbers appear on the atom pair.
Tip: Mapping atom pairs can significantly narrow your search results. Start by mapping the minimum number of atom pairs needed to focus your query.
Learn More
Drawing and Editing Structures