What is in the space between atoms?
I understand that molecules are constantly being formed from collisions and such, but what I do not understand, is, on a tiny level, within the level of the atom, what is in between? 'Air' is not the answer, what if we were talking about the molecules and therefore the atoms between air! What's there! Is it matter? Is it just 'nothingness?' Is it subatomic particles?
Similarly, what is space? For example, in outer space, there is ideally a vacuum. What is in a vacuum, if not atoms? What is in space, if not atoms?
I have had these questions for as long as I could comprehend 'open space.'