What is a reaction called in which a chemical change takes place?

A reaction in which a chemical change takes place is defined as a chemical reaction. This type of reaction involves the breaking and forming of chemical bonds, resulting in the transformation of substances into new products with different properties from the reactants. Examples include combustion, oxidation, and synthesis reactions, where the composition of the substances involved changes significantly.

In contrast, a physical reaction involves changes in the state or appearance of a substance without altering its chemical composition, such as when ice melts into water. A nuclear reaction, on the other hand, typically involves changes to the nucleus of an atom, leading to the formation of different elements or isotopes, which is not focused on chemical changes but rather on nuclear stability. Lastly, a biochemical reaction refers specifically to reactions that occur in biological systems, often catalyzed by enzymes, which involve chemical changes but are defined by their biological context rather than a general category. Thus, the term "chemical reaction" is the most appropriate descriptor for a general chemical change.