I do know a little about chemistry and a little about biology. But entire libraries have been written about both subjects. Scientists know lots about both, and the subjects overlap. The thing is, though, that once you wade through enough to see the end of what is known, you get to the place where you can see some of the unknown. How much is unknown is unknown. The knowledge and the models break down.
But we can understand some things by understanding the models.
Take water for example. We know that water is two hydrogen atoms and one oxygen. Electrons have properties of both matter and energy–chemists used to talk about electrons orbiting a nucleus–beginning science classes still do. But current models talk about electrons setting up standing waves, so that they occupy a particular statistical space around the nucleus, or around the nuclei in the case of a covalent bond.
The hydrogen atoms have a weak positive charge, and the oxygen atom has a weak negative charge. So the molecules attach to each other, and form what are called hydrogen bonds. But the kinetic energy of heat present in the water knocks the molecules around and breaks those bonds. The molecules continually attach and detach from each other.
That explains how water flows, and how it is also able to bead up.
There are models that go into incredible detail to explain how it happens, and there are mathematical equations that back up those models. The math gets pretty intensive, but the model allows a visual approximation.
On the molecular scale, water is pretty sticky.
So you can understand how it works, but do you really understand it?