chemical reaction

American  

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

noun

1. Chemistry. reaction.

---

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

---

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.

---

Etymology

Origin of chemical reaction

First recorded in 1780–90

Example Sentences

The leak also depletes the source for a chemical reaction, which is generating heat that, in turn, accelerates the reaction in a process called “thermal runaway.”

From Los Angeles Times • May 24, 2026

Workers at Catalyst Refiners Inc. in Institute, W.Va., were cleaning and decontaminating a metal processing site—in preparation for closing it down—when a chemical reaction created dangerous hydrogen sulfide gas around 9:30 a.m.

From The Wall Street Journal • Apr. 22, 2026

Fire Administration, potentially leading to a process known as thermal runaway, in which the battery ignites through a self-sustaining chemical reaction that is impossible to stop until it runs out on its own.

From Los Angeles Times • Apr. 6, 2026

The crystals are driven by a chemical reaction similar to the one used to power rockets.

From Science Daily • Mar. 19, 2026

“But what causes them to mix, Horace? This chemical reaction you speak of—what is it?”

From "Snow Falling on Cedars: A Novel" by David Guterson

Related Words

• vicious circle