(chemistry only) Define atom economy as a measure of the amount of starting materials that end up as useful products.

Atom economy is a key concept in chemistry that measures the efficiency of a chemical reaction in terms of how much of the starting materials are converted into useful products. It is calculated by comparing the relative formula mass of the desired product to the total relative formula mass of all products formed in the reaction. A high atom economy indicates that a greater proportion of the reactants are transformed into valuable products, which is crucial for sustainable development and economic viability in chemical processes. This concept helps chemists design reactions that minimize waste and maximize resource use.