Why does chemistry involve the study of the changes in the world at a submicroscopic level?

Answer;

The changes you see with your eyes all begin with changes at the submicroscopic level, and that is what chemistry explains.

Explanation;

-Chemistry is the study of matter and the changes that it undergoes. Chemistry is commonly viewed at three different levels of representation; macroscopic, submicroscopic and symbolic, that combine to enrich the explanations of chemical concepts.

-Submicroscopic world entails things that can be observed with a microscope, they can not be seen by our naked eyes. Atoms and molecules are submicroscopic and it is their behavior that determines the macro behavior of chemicals in bulk.