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.

---

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

In certain scenarios, nearly half of the modeled particles transported newly created organic molecules from the broader protosolar nebula into Jupiter's circumplanetary disk, where they were incorporated into the growing moons with little chemical change.

From Science Daily • Mar. 1, 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

They are produced in fall, products of a chemical change involving an increased concentration of sugars in the leaves.

From Seattle Times • Dec. 2, 2022

A chemical change was taking place in him.

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