Final answer:
A chemical reaction that combines two or more reactants to form a single product is called a combination or synthesis reaction, also known as a composition reaction.
Step-by-step explanation:
The type of chemical reaction where two or more reactants combine to make one product is known as a combination reaction or synthesis reaction. An example of this is the combination of sodium (Na) and chlorine (Cl2) to form sodium chloride (NaCl). The general equation representing a combination reaction is A + B → AB, indicating that reactants A and B combine to form a single product AB.
In a composition reaction, multiple reactants combine to create a single substance, defining this as another term for a combination or synthesis reaction. This type of reaction is foundational in understanding how more complex molecules are formed from simpler ones.