Monoatomic in a sentence as an adjective

A monoatomic planar fractal void of some description might work.

That one has my favorite chemistry quote: At seven hundred freaking degrees, fluorine starts to dissociate into monoatomic radicals, thereby losing its gentle and forgiving nature.

Monoatomic definitions

adjective

of or relating to an element consisting of a single atom; "helium and argon are monatomic gases"

See also: monatomic