Final answer:
Physical changes affect the form of matter without altering the molecular structure, while chemical changes involve breaking and forming new bonds, resulting in new substances with different properties.
Step-by-step explanation:
Difference Between Physical and Chemical Changes
The main difference between a physical change and a chemical change concerns the molecules and bonds within a substance. A physical change affects the form of matter without changing its molecular structure, such as ice melting into water. During this change, the mass, number of atoms, and number of molecules remain consistent, while the arrangement of particles may differ. Conversely, a chemical change involves the breaking and/or forming of bonds between molecules or atoms: this transforms the original substances into new substances with different properties. Chemical reactions signify a chemical change where elements or compounds recombine to form new chemical species, each with distinctive physical and chemical properties that are often hard to reverse compared to a physical change.
Examples of physical changes include the melting of ice, the evaporation of water, or the grinding of a rock. Examples of chemical changes, on the other hand, include burning gasoline, iron rusting, and baking a cake. In the first set, substances retain their molecular compositions, while in the second set, new molecular compositions result from the reactions, indicating a chemical change.