Circular Economy & Materials
Atom economy
A green chemistry metric measuring what share of the atoms in the reactants ends up in the desired product — the rest becomes waste by design.
Expert review openNo editor-accepted expert review yetDefinition
The percentage of the total formula weight of all reactants that is incorporated into the desired product: % atom economy = (formula weight of desired product ÷ sum of formula weights of all reactants) × 100. Developed by Barry Trost (1991), it is the second of the Twelve Principles of Green Chemistry: synthetic methods should maximise incorporation of all materials used into the final product.
References
Definition and formula; Trost (Science 1991) origin; worked example (50% at 100% yield); relationship to other green metrics.
Overview
What it means
Atom economy complements yield: a reaction can have 100% yield yet poor atom economy if much of the reactant mass ends up in by-products (the classic ACS worked example scores 50% despite perfect yield).
Because it is calculated from the balanced equation, it measures intrinsic wastefulness of a route before any process considerations such as solvents, which are captured by complementary metrics (E-factor, process mass intensity).
How it is used
Chemists use atom economy to compare synthetic routes at the design stage, favouring addition and rearrangement reactions over substitutions and eliminations. In industry it is combined with yield, E-factor and PMI to drive greener processes, especially in pharmaceuticals.
Why it matters
Atom economy embeds waste prevention — rather than end-of-pipe treatment — into chemical design. It is a foundational concept linking chemistry to circular-economy and pollution-prevention goals.
Review
Public comments appear only after editor acceptance. Draft comments stay in the review queue.
Reviewers choose the definition or an overview paragraph, leave a comment or replacement, and attach evidence or a source link.
Editors compare reviewer cards side by side. AI may help find agreement, conflicts, unsupported claims and possible source issues.
Only an editor-accepted synthesis changes the public page. Reviewer identities are shown only with consent and verification.
Submitted reviews stay private until accepted.
Loading verified endorsements… Endorsements are not votes and never determine publication.
Endorse this definition
Endorse the exact version shown here. This is not a vote, and publication remains an editorial decision.
Review board
Comment on a specific line. Each reviewer stays separate until an editor accepts a merged draft.
Each person comments on the definition or overview in their own draft card, with role, evidence and suggested wording kept together.
AI can compare comments against the current text, flag conflicting claims, surface missing evidence and identify where reviewers agree.
An editor merges compatible suggestions into a draft change, checks sources, records disagreements and decides what can be published.