* New substances are formed: Iron (Fe) and oxygen (O2) react to create iron oxides (like Fe2O3, rust). These oxides have different properties than the original iron and oxygen.
* Chemical bonds are broken and formed: The reaction involves breaking the bonds within oxygen molecules and forming new bonds between iron and oxygen atoms.
* Irreversible (generally): While some iron oxides can be broken down, the process of rusting is generally irreversible.
In contrast, physical changes:
* Only alter the appearance or state of a substance, not its chemical composition.
* Are often reversible.
Examples of physical changes:
* Melting ice (water changes state from solid to liquid, but remains H2O)
* Cutting a piece of paper (changing the shape but not the chemical makeup).
