One atom, of carbon, is the smallest unit of carbon, that still behaves like carbon. We can just barely, by modern techniques, see one atom by itself. However, in situations where we can see a single atom, or a few atoms, they behave as we would expect.
We have a word, in English, called a 'dozen', that's 12 of anything. And 12 carbon atoms behave pretty much the same as 1 does.
We use a term, in chemistry, called a 'mole', and its just the name of an Avogadros's of things. You can consider a mole of eggs(although that's way too many to have in one place at one time for real) -- a mole is no different than a dozen.
You can draw a chemical reaction:
2 C + O2
You can pretend those coefficients are atoms, or pretend they refer to a dozen. But if you call them moles, you can use the atomic weight of carbon, and the formula weight of diatomic oxygen, to actually weigh out or otherwise measure the reactant and product quantities.
As entertaining as it is to write out the value of Avogadro's number is, its really no different than a dozen.