Final answer:
A chemical change involves the formation of new substances with different properties and a different chemical formula. A physical change, on the other hand, does not involve the formation of new substances and the chemical formula remains constant.
Step-by-step explanation:
A chemical change, also known as a chemical reaction, is a process in which bonds are broken and/or formed between molecules or atoms. This results in the formation of new substances with different properties compared to the original substances. In a chemical change, the chemical formula of the substances involved will be different because new substances are formed.
On the other hand, a physical change is a change that can be observed or felt, but does not involve the breaking or forming of bonds. During a physical change, the arrangement of particles may change, but the mass, number of atoms, and number of molecules will stay the same. Therefore, in a physical change, the chemical formula of the substances remains constant.