Q:

Is there a word for an atomic unit of flour?

Is there a word for an atomic unit of flour? If so, what is it?
I use atomic unit not to refer to chemical compound, molecule, or atom, but rather the individual particle of flour after milling. In the same way that grains of sand can be different sizes, I'm aware flour can also be different sizes, but I am trying to distinguish from a clump of flour, which is not a byproduct of milling, but adhesion.
Grain does not seem correct, as flour is composed of particles of a grain, with grain being a unit of corn, wheat, etc. However, if there is justification as to why it is actually the most correct, that is fine.
For instance, if the word was foo, 

"There are a few foos of flour on the counter."

A:

Specks of flour: 

a very little bit or particle:

We haven't a speck of sugar.

Dictionary.com 
From: Great British Bake Off:,

Lift the rest of the flour into the bowl and continue folding in until you no longer see streaks or specks of flour. Transfer the mixture to...

A:

As mentioned in your question itself, you may call it a particle of flour.

"There are a few particles of flour on the counter."

M-W:

particle
noun
1 a :  a minute quantity or fragment
b :  a relatively small or the smallest discrete portion or amount of something

Usage example: Google search of "particles of flour"

A:

How about a mote of flour?
From the American Heritage Dictionary:

mote (n) A very small particle; speck.

