The atom economy of a chemical reaction is a measure of the amount of starting materials that become useful products. Inefficient, wasteful processes have low atom economies. Efficient processes have high atom economies, and are important for sustainable development, as they use fewer natural resources and create less waste.

Companies want to maximise as much product as possible to allow for maximum profits. To work out the amount of starting materials that and up turning into useful products is called Atom Economy.

% of atom economy = Mr of useful products x100

Total Mr of all products

e.g. C2H5OH -> C2H4 + H2O

Mr: C2H5OH = (12×2) +(1×6) + 16 = 46 

C2H4 = (12×2) + (1×4) = 28

H2O = (1×2) + 16 = 18

Atom Economy = 28 x100 = 61%

(28+18)