Nominally an atom. However, some element's atoms combine with one another as molecules. For example, carbon is usually extant as C2. In diamonds carbon exists as C4 molecules. Such compounds that exist as elements in different forms are called allotropes.
the smallest particle is an atom there can be billions on the fingertip of your nail!
The smallest quantity of an element is an atom.
a quark or if you mean the smallest element hydrogen
ATOM
the smallest element is hydrogen of which its valency is one.
The atom is the smallest unit of an element that has all the properties of the element.
The smallest identifiable unit of an element that retains the properties of the element is an atom.
The smallest particle of an element is called an atom.
An atom is the smallest particle that is still recognisably the element
atom is the smallest part of element
a pixel is the smallest element in an electronic image
The smallest unit of a chemical element is the atom.