chemical reaction

American  

[kem-i-kuhl ree-ak-shuhn] / ˈkɛm ɪ kəl riˈæk ʃən /

noun

1. Chemistry. reaction.

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chemical reaction British  

noun

1. a process that involves changes in the structure and energy content of atoms, molecules, or ions but not their nuclei Compare nuclear reaction

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chemical reaction Cultural  

1. A process in which atoms of the same or different elements rearrange themselves to form a new substance. While they do so, they either absorb heat or give it off.

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Etymology

Origin of chemical reaction

First recorded in 1780–90

Example Sentences

Hydrogen sulfide smells like rotten eggs and can be produced by a chemical reaction and by some organic material, such as sewage.

From The Wall Street Journal • Apr. 22, 2026

Form’s iron-air batteries generate electricity through a chemical reaction involving oxygen, water and iron powder that mimics how old pieces of metal gather rust.

From Barron's • Feb. 24, 2026

However, the chemical reaction that links amino acids together follows the same basic rules everywhere, making the discovery especially important.

From Science Daily • Jan. 21, 2026

Earlier this year, the South Coast air district learned about another fiery chemical reaction brewing inside El Sobrante Landfill in Corona.

From Los Angeles Times • Nov. 19, 2025

Even worse, though, a chemical reaction that was occurring in the high heat of the reactor core was producing highly flammable hydrogen gas.

From "Meltdown" by Deirdre Langeland

Related Words

• vicious circle