Chemistry – Chemical reactions - Physical and chemical changes | e-Consult

This change is a chemical change.

When the copper wire is heated, it reacts with oxygen in the air to form copper oxide (CuO). This is evident by the change in colour from the shiny, reddish-brown copper to a dull, black oxide.

At a particle level, this involves the breaking of chemical bonds within the copper atoms and the formation of new chemical bonds between copper and oxygen atoms. The particles (atoms and molecules) are rearranged to form a new substance with different chemical properties. A physical change only involves changes in state or shape, without altering the chemical composition of the substance.