The changes that matter experiences are classified as either physical or chemical.
A physical change is any alteration to the size, shape, or state of a substance. For example, melting an ice cube. It just changed from solid to liquid.
A chemical change, on the other hand, occurs when matter changes into a new substance and has a new chemical property. There are different signs of chemical change. There is the change in color, change in odor, formation of gas, formation of solid, and change in energy.