Step-by-step explanation:
Every element is made up of atoms which cannot be further divided into simpler substances.
For example, a piece of zinc metal will only contains atoms of zinc and no there element.
Since, these atoms are the same as the element itself. Hence, the element still retain its properties because there no other different element is present in it.
Thus, we can conclude that the smallest unit that can exist as an element and still have the properties of that element is an atom.