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

Industrial catalysts -- substances that reduce the amount of energy required for a given chemical reaction -- help manufacturers boost reaction speed, yield or efficiency when producing key materials.

From Science Daily • Nov. 21, 2025

The facility housed around 100,000 lithium-ion batteries, which are exceptionally dangerous when ignited because they burn extremely hot and cannot be extinguished with water, which can trigger a violent chemical reaction.

From Los Angeles Times • Oct. 17, 2025

“You’ve smelled rotten eggs? That’s sulfur dioxide, released from the chemical reaction of rotting organic material. This is going to stink just like that.”

From "October Sky" by Homer Hickam

Related Words

• vicious circle