Atomicity refers to the smallest, irreducible, building block material. The core concept is that as you build things after defining the smallest, individual elements, then the possibility of mixing and matching increases, thus improving the scope of building Lego like structureLego like structure
An easier way of understanding Atomicity is by comparing it with Lego Box. Lego Box, contains a set of 'blocks', a basic unit of the game.
Lego Blocks are the smallest component. You can't break it into smaller component.
By mix and match, you can build complex components.
There is a defined consistency/rules, you have to follow those to build stable results.
There are endless combinations.
Lego sells it in 'thematic form'. One contains flight, other contains cr...