chemical change

American  

[kem-i-kuhl cheynj] / ˈkɛm ɪ kəl ˈtʃeɪndʒ /

noun

1. Chemistry. a usually irreversible chemical reaction involving the rearrangement of the atoms of one or more substances and a change in their chemical properties or composition, resulting in the formation of at least one new substance.

   The formation of rust on iron is a chemical change.

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Usage

What is a chemical change? A chemical change happens when one chemical substance is transformed into one or more different substances, such as when iron becomes rust. Chemical changes occur through the process of chemical reactions, and the resulting substances have different properties because their atoms and molecules are arranged differently. A chemical change is different from a physical change, which doesn’t rearrange atoms or molecules and produce a completely new substance. Ice melting into water is an example of a physical change.

Etymology

Origin of chemical change

First recorded in 1755–65

Compare meaning

How does chemical-change compare to similar and commonly confused words? Explore the most common comparisons:

• physical change vs. chemical change

Example Sentences

See Examples For:

chemical change

Researchers may eventually use similar mechanisms to create artificial muscles or other materials that move when triggered by a chemical change in pH.

From Science Daily ● Jul. 27, 2026

Using human Alzheimer's brain cells and other experimental models, the team discovered a chemical change that can push the brain's immune response into overdrive.

From Science Daily ● May 31, 2026

That said, not many products can be frozen, thawed, and refrozen without any structural or chemical change.

From Salon ● Jul. 5, 2025

The high-temperature firing process produces a chemical change in the clay, creating an artificial rock of sorts.

From Seattle Times ● Jun. 12, 2023

A chemical change was taking place in him.

From "The Heart is a Lonely Hunter" by Carson McCullers