A change in the state of a material is known as what kind of change?

A change in the state of a material is identified as a physical change. This type of change involves alterations in the form, appearance, or state of a substance without changing its chemical composition. For example, when water freezes to become ice or melts to become liquid, these are physical changes because the molecular structure of the water (H2O) remains the same throughout the process.

In contrast to physical changes, a chemical change involves the transformation of substances into new entities with different chemical properties. These may include reactions like rusting iron or burning wood, where the original substances are fundamentally altered.

Biological changes pertain to alterations that occur in living organisms or ecosystems, while thermal changes specifically refer to changes in temperature that can accompany both physical and chemical processes but do not define a change in the state of material itself. Therefore, recognizing that changes in state—such as from solid to liquid to gas—are purely physical processes is key to understanding the concept.