What is the definition of physical and chemical changes?

Physical change, a change that occurs physically, and can also be seen physically. But chemically, it's a change that occurs within the chemical, and most likely not be seen within the eyes, but, has a different charater afterward.

A physical change in a substance doesn't change what the substance is. In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed. For example, if a piece of paper is cut up into small pieces it still is paper.