The smallest unit of an element that retains all the characteristics of that element is called a (n)

A)

atom.

B)

compound.

C)

molecule.

D)

proton.

The smallest unit of an element that retains all the characteristics of that element is called an A. atom.

Atoms consist of protons, electrons, and neutrons, but they are particles and don't have the characteristics of the element which is why D is incorrect. B and C are not the smallest units - atoms are smaller than them.