Question

copper is made of atoms
an atom is the smallest part of an element. atoms are the building blocks of all materials on earth.
in a wire made of copper, in just 1 mm of this wire, there are billions of copper atoms. copper is an element on the periodic table.
what is the very smallest piece of copper possible?
a copper atom
a copper nugget
a copper wire

Explanation:

Atoms are the smallest units of an element. Copper is an element, so its smallest piece is a copper atom. A copper nugget and copper wire are macroscopic objects made of many atoms.

Answer:

a copper atom