# How do we know that electrons overlap to form chemical bonds?

How? Well there is a whole scientific field devoted to the interactions between atoms, and the field is called $\text{chemistry}$..........
The modern chemical bond, $\text{the covalent bond}$, is conceived to be a region of high electron density between 2 positively charged nuclei, such that internuclear repulsion is negated and a net attractive force results from the like and unlike charges.