Atom economy means how much of the starting materials in a chemical reaction actually end up in the final product.
- If most atoms from the reactants become part of the product, the reaction has high atom economy.
- If many atoms are wasted as by-products, the atom economy is low.
It is calculated like this: Atom economy (%)=(Mass of desired product/Mass of all reactants)×100
In short: It shows how “efficient” a reaction is with respect to using atoms.