These four icons are found at the bottom of the left-side menu in the structure editor:
Last updated 8/12/2025
is used to assign a reaction role. Once a substance is drawn, you'll select this tool and then hover over the substance of interest which will highlight red. Once clicked, a Reaction Roles menu will pop-up where you can select the role of interest:
Last updated 8/12/2025
is used to map atoms in a reaction, meaning that you can specify corresponding pairs of atoms from the reactant to the product. You'll select this tool and then the atom of interest in the reactant, then the atom of interest in the product. Each mapped pair will have a number assigned. The example below is found in the CAS Help:
Last updated 8/12/2025
is used to mark bonds that are broken and/or formed in a particular reaction. In the example below, this icon was clicked and then the bond highlighted below was selected. The bond will have a double hashmark placed on it, meaning that it must be broken in the reaction:
Last updated 8/12/2025
is used to draw the reaction arrow. Once the arrow is drawn, substance(s) on either side are assigned as either Reactants or Products. The 'Assign and Reaction Role' tool above can be used to change these. In the example below, as the substance appears before the arrow, it has been assigned as a Reactant:
Last updated 8/12/2025
