Atomic notes
An “atomic note” is a note where we have a single concept. This concept doesn't dictate note size, but atomic notes tend to be very small so that they don't cover more than a single thing at a time. The atomicity, then, comes from the number of ideas or concepts covered in a single note, not its size.
This concept came from Sönke Ahrens' book How to take smart notes / (How to Take Smart Notes), which describes an implementation of Niklas Luhmann's zettelkasten method.
I've created the term Molecular notes for long / big notes.