The changes matter undergoes are classified as either physical
changes or chemical changes. A process in which a substance changes its physical
form or appearance but not its basic composition is called a physical change.
Can you name some physical changes?
Chemical changes are always changes in the composition and form
of a substance. In a chemical change, matter is transformed completely into
different materials and new substances are formed. The type of chemical changes
that a substance can undergo are determined by its chemical properties. Can
you name some chemical changes?
and Changes of Pure Substances..p59