a process that involves rearrangement of the molecular or ionic structure of a substance, as distinct from a change in physical form or a nuclear reaction.
a reaction where particular set of chemicals changes into another form without changing their nuclei just the transfer or sharing of electrons and formation and breaking of bonds is called as chemical reaction.
example- formation of water, photosynthesis etc.
but if there is a change in nuclei than it would be called as nuclear reaction.
