Glossary
physical change
A physical change alters a substance's form, state or shape without making a new substance — melting, boiling, dissolving or cutting.
A physical change alters how a substance looks or what state it is in, but not what it is. Melting ice, boiling water, dissolving sugar and cutting a metal all leave the same substance behind, so they are physical. A physical property is a quality you can observe without changing the substance — its density, color, melting point or state. Because no new substance forms, a physical change is usually easy to reverse: freeze the water and you have ice again. The common error is to call any dramatic change "chemical". The test is not how it looks but whether a new substance has appeared — that is what makes a change chemical.
Taught in
Related terms
- chemical change — A chemical change makes one or more new substances; the evidence is a gas, a precipitate, a color change, or heat or light.
Source: OpenStax Chemistry 1e and Chemistry: Atoms First 1e, first editions (CC BY 4.0). Each definition restates the Chemistry guide in this exam, which carries the per-source citations on its own page. (OpenStax 1e accessed 2026-10-08)