During a chemical change, the following occurs:
- The bonds between atoms or molecules in the reactants are broken and new bonds are formed, resulting in the rearrangement of atoms.
- One or more substances are transformed into new substances with different chemical properties and compositions.
- This change is often irreversible and results in the formation of substances that are chemically different from the starting materials.
- Chemical changes usually involve observations such as temperature change, light emission, color change, formation of gas bubbles, formation of a precipitate (solid), or change in smell or taste.
- No atoms are created or destroyed during the process; they are simply rearranged to form new molecules.
Examples include burning a candle (which produces carbon dioxide and water), rusting of iron, photosynthesis, and the decomposition of water into hydrogen and oxygen gases. In summary, a chemical change is a process where one or more substances are converted into one or more new substances through the breaking and forming of chemical bonds, resulting in new chemical identities and properties. This is different from a physical change where the substance's chemical identity remains the same, such as ice melting into water.
