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.

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".