'Every time you want to consider an idea in isolation, separate it from its context' - This is my rule of thumb to creating atomic notes.

Many people stress out on how atomic their notes should be.

Is the note too long? Is it too short? How many ideas do I have in there? By stressing so much on the structure, they lose the focus on what really matters: the content of the notes.

The ideas get lost in structure.

So, when it comes to giving structure to notes, I follow Milor's Razor:

"Structure needs to be earned"

Don't be afraid of creating Very Long Notes (VLN) if that is what is coming to mind at the time of creating or expressing ideas. After the notes are written, you can still break them down.

Any ideas in that VLN that you would like to think about in isolation? Perhaps compare against other ideas? Perhaps expand on its own or apply to another context?

Then extract the idea on its own atomic note, and leave a link in the original VLN (now smaller).

Is that new note "atomic"?

Perhaps.. for a while.

Perhaps as your understanding grows, you want to separate even more the details of that note. You want to focus on a specific characteristic of a thing, or you want to explore the different perspectives on an idea. Go ahead and break it down further.

Does it mean the note was not atomic before?

We can break ideas almost infinitely, so what really matters is not that it is "atomic" in the sense that it can't be further broken down. What matters is that it focuses on a single idea that YOU care about.

If a note has more than one idea you care about, then break it down.

Give the idea its own home, separated from all the noise from surrounding ideas. Break it down and keep a link back to its original context.

As the time goes by, at the time you are writing things down you will immediately recognise when an idea should have its own note. Until then, feel free to follow this rule of thumb and stress a bit less about your notes being "atomic"